Current Trends in Electrochemistry

Current Trends in Electrochemistry 41st Meeting of the Electrochemisty Group of the Spanish Royal Society of Chemistry 1st French‐Spanish Atelier/Workshop on Electrochemistry

Paris 6th July – 9th July 2021

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Table of Contents

Sponsors & Exhibitors ...... 3 Preface ...... 4 Organizers ...... 5 Scientific Advisory Board ...... 5 Organizing Committee ...... 5 Site map ...... 6 Invited speakers ...... 7 Program ...... 8 Detailed Program ...... 9 Tuesday July 06th, 2021 ...... 10 Wednesday July 07th, 2021 ...... 34 Thursday July 08th, 2021 ...... 69 Friday July 09th, 2021 ...... 106 Posters ...... 142

2 Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Sponsors & Exhibitors

3 Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Preface

La Reunión del Grupo de Electroquímica de la RSEQ es la cita anual que desde finales de los años 70 reúne a toda la comunidad Electroquímica española entorno a un único evento para discutir los últimos avances en nuestro campo. La calidad científica de las comunicaciones presentadas ha ido siempre acompañada por la gran calidad humana de los participantes y por este motivo, las reuniones del Grupo de Electroquímica se han convertido en lugar de reencuentro de muchos amigos.

Esta realidad ha ido evolucionando con el paso del tiempo. Pero sobre todo desde hace algo más de una década y debido principalmente a la fuerte crisis económica vivida en España, el número de electroquímicos/as formados en España que han emigrado y hoy en día lideran grupos importantes en otros países europeos y EE.UU. no ha parado de crecer. Nuestra intención desde el Comité Organizador es que la XLI Reunión del Grupo de Electroquímica organizada en Paris (Francia) en 2021 sirva para reagrupar a todos los electroquímicos formados en España, tanto emigrados como residentes, y además abra una nueva vía hacia la internacionalización de las reuniones del grupo. En este sentido, creemos que la organización de jornadas binacionales o europeas como eventos asociados a la Reunión ayudarán a dar visibilidad a nuestra investigación. La organización del 1st French-Spanish Atelier/Workshop on Electrochemistry supone por tanto la primera de estas jornadas binacionales en la que el objetivo es estrechar los lazos de colaboración con la comunidad electroquímica francesa.

Je voudrais remercier la Subdivision Électrochimie Française de la SCF pour son implication dans l’organisation de cette journée Atelier.

This is a great pleasure to welcome you all at the Current Trends in Electrochemistry meeting (https://cte-gerseq2020.org/). Organizing this hybrid event (on line and on site) represents a great honour and responsibility for all of us. For this reason, we would really like to thank all of you for supporting us during these last two difficult years where we had to fight against the sanitary crisis to accomplish the organization of this event.

Finally, let us wish you a successful and productive meeting.

Yours sincerely,

On behalf of the organizing committee, Carlos M. SANCHEZ-SANCHEZ Chargé de Recherche CNRS LISE UMR 8235 – Sorbonne Université Paris (France)

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Organizers

Electrochemistry Group of the Spanish Royal Society of Chemistry (GE‐RSEQ) and the sub‐ division of Electrochemistry of the French Chemical Society (E‐SCF).

Scientific Advisory Board

Manuel Blázquez Universidad de Cordoba (SPAIN) Enric Brillas Universidad de Barcelona (SPAIN) Christine Cachet‐Vivier Université Paris Est Créteil (FRANCE) Thomas Doneux Université Libre de Bruxelles (BELGIUM) Iluminada Gallardo Universidad Autónoma de Barcelona (SPAIN) María Aránzazu Heras Universidad de Burgos (SPAIN) Vicente Montiel Universidad de Alicante (SPAIN) Nadine Pébère CIRIMAT‐CNRS‐Toulouse (FRANCE) Hubert Perrot Sorbonne Université‐CNRS (FRANCE) Ignacio Sirés Universidad de Barcelona (SPAIN) José Solla‐Gullón Universidad de Alicante (SPAIN)

Organizing Committee

Chairman:

Carlos Sanchez‐Sanchez Sorbonne Université – CNRS

Honorific Chairman

Marc Fontecave Collège de France‐CNRS

Secretary

Maria Gomez Mingot Collège de France‐CNRS

Members:

Antoine Loiret Sorbonne Université ‐ Christine Mousty Université Clermont Auvergne ‐ CNRS ‐ SCF Beatriz Puga Commissariat à l’Energie Atomique ‐ CEA Saclay Encarnacion Torralba Université Paris Est Créteil ‐ CNRS Neus Vila Université de Lorraine

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Site map at Sorbonne Université Campus Pierre et Marie Curie, 4 Place Jussieu 75005 Paris

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Invited speakers

SANCHEZ Clément LCMCP, Collège de France, FR TIRADO José Luís Univ. de Cordoba, SP SAUVAGE Jean‐Pierre CNRS, Univ. de Strasbourg, FR SAEZ Cristina Univ. of Castilla La Mancha, SP MAILLARD Frederic LEPMI, Grenoble, FR SIRES SADORNIL Ignacio LEMMA, Univ. de Barcelona, SP COLINA Alvaro Univ. de Burgos, SP LABORDA Eduardo Univ. de Murcia, SP LEMAITRE Frederic Sorbonne Univ.‐ENS Paris, FR MIOMANDRE Fabien PPSM – ENS, FR BOUFFIER Laurent Univ. Bordeaux, FR MARTIN‐YERGA Daniel Univ. of Warwick, UK CUESTA Angel Univ. of Aberdeen, UK SOLLA‐GULLON Jose Institute of Electrochemistry, UA, SP GARCIA‐SEGURA Sergi Arizona State Univ., USA GUIRADO Gonzalo Univ. Autonoma de Barcelona, SP GARCIA‐ARAEZ Nuria Univ. of Southampton, UK LEROUX Yann ISCR, FR CHATENET Marian LEPMI, Grenoble, FR LUCAS Ivan T. LISE, Sorbonne Univ., FR GAUTIER Christelle Lab. MOLTECH‐CNRS, FR NOEL Vincent ITODYS Univ. de Paris, FR ETIENNE Mathieu LCPME, Univ. de Lorraine, FR RECIO Francisco Univ. Autónoma de Madrid, SP ESCUDERO‐ESCRIBANO Maria Univ. of Copenhagen, DK BUCHER Christophe ENS Lyon, FR GUILLE‐COLLIGNON Manon Sorbonne Univ., FR

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Current Trends in Electrochemistry 41st Meeting of the Electrochemistry Group of the Spanish Royal Society of Chemistry 1st French‐Spanish Atelier/Workshop on Electrochemistry

Detailed Program

Book of Abstracts

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Detailed Program CURRENT TRENDS IN ELECTROCHEMISTRY 2021, Paris 6‐9 July 2021

Tuesday July 06, 2021 Wednesday July 07, 2021 Thursday July 08,2021 Friday July 09, 2021

8h00 – 8h15h Opening Ceremony 8h00 – 8h15h 8h00 – 8h15h Opening Workshop

8h15 – 9h00 Plenary lecture 8h15 – 9h00 Plenary lecture 8h15 – 9h00 Plenary lecture Clément SANCHEZ José Luis TIRADO Jean‐Pierre SAUVAGE 9h00 – 9h20 Angela Molina Room 24 Room 34A Room 24 Room 34A 9h00 – 9h15 J.A. Coca J. M. Feliu Maria Clemente 9h00 – 9h25 Angel Escudero Cuesta 9h20 – 9h40 Albert Serrà 9h15 – 9h30 J. Carretero R. Rizo Escribano González 9h40 – 10h00 Aida Martín 9h30 – 9h45 E. García A. González Gaitán Orive 9h25 – 9h50 Frédéric Laurent 10h00 – 10h30 Coffee break 9h45 – 10h Antonio R. Maillard Bouffier Molina Madueño 10h30 – 10h50 Paula Sebastián 10h– 10h15 E.Mundara J.L. Olloqui y‐Guilarte Sariego 9h50 – 10h15 Jose Solla Eduardo 10h50 – 11h10 María Arnaiz 10h15 – 10h45 Coffee break Gullón Laborda Room 24 Room 34A 10h45 – 11h X.R. Novoa J. González 10h15 – 10h45 Coffee break 11h10 – 11h25 C. Leger E. González‐ 11h – 11h15 L. López T. Binninger Romero Chalarca 10h45 – 11h10 Marian Frédéric 11h25 – 11h40 L. Merakeb R. Miranda‐ 11h15 – 11h30 J. J. García A. Boudet Chatenet Lemaitre Castro Jareño 11h40 – 11h55 R. Arán‐Ais S. Guerrero 11h30 – 11h45 C. Mariño M. Brites Manon Martínez Helú 11h10 – 11h35 Francisco J. Guille‐ Recio 11h55 – 12h10 O.Gutierrez A. de la 11h45 – 12h J. Izquierdo J.Fernández Collignon Escosura Vidal 12h – 12h15 Belén Díaz J. García 12h10– 13h30 General Assembly Cardona 11h35 – 12h Nuria Vincent 12h15 – 12h30 Brenda Garcia‐ Noel GE‐RSEQ Hernández Y. Holade Araez Concepción

12h30 – 14h Lunch 12h – 13h30 Lunch

Origalys HTDS 13h30 – 14h Poster Flash Poster Flash

13h30 – 15h Lunch Session 1 Session 2

15h – 15h15 G. Díaz‐ V. Serafin 14h – 15h30 Christophe Ivan T. Sainz González 14h – 14h25 Poster Poster Bucher Lucas 15h15 – 15h30 F. Martínez N. Felipe Session 1 Session 2 Yann Daniel 14h25 – 14h50 15h30 – 15h45 B. Avila A. Valverde Leroux Martín‐ Bolivar P01 ‐ P32 P33 ‐ P66 Yerga 15h45 – 16h T. Andreu H. Cunha‐ Christelle Gonzalo Silva 14h50 – 15h15 Gautier Guirado 16h – 16h15 J.Hernánde R. Jiménez‐ z‐Ferrer Pérez 16h15‐16h45 Coffee break 15h30 – 16h Coffee break 15h15 – 15h45 Coffee break 16h45‐17h00 G. Rosello‐ M. Revenga 16h – 16h15 E. Mousset E. Pastor Cristina Fabien 15h45 – 16h10 Marquéz Sáez Miomandre

Master and 17h00‐17h15 R. Oriol E. Valero 16h15 – 16h30 J.M. Ortiz B. Oraá Ignacio Alvaro Poblete 16h10 – 16h35 15h ‐ 18h Doctoral Programs Sirés Colina Student 17h15‐17h30 V. Poza J.M. Díaz‐ 16h30 – 16h45 J.J. Lado M.González Sadornil Nogueiras Cruz Ingelmo presentations 17h30‐17h45 M. Carvela F. Prieto 16h45 – 17h G. Sánchez M. Pérez Sergi Garcia Mathieu Soler Obrero Estebanez 16h35 – 17h Segura Etienne

Master Programs Closing Ceremony 17h‐18h30 17h – 17h30 presentation

Oral Communication ON LINE Oral communication ON LINE Oral Communication ON SITE

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Tuesday July 06th, 2021

15h30 - 19h DEFENSA PLAN DE INVESTIGACION (ONLINE)

Tribunal 1D Tribunal 2D Tribunal 3D Alvaro Garcia Diana Elena Ciurduc Andres N. Martin Alberto Romero Lucia Lope Solis Angela Fernandez Laura Sierra Kevin Rosales Segovia Esteban Guillen Ivan Salmeron Zhao Lele Romayssa Amrine Sabrina Berling

15h30 - 19h DEFENSA TFM (ONLINE)

Tribunal 1 Tribunal 2 Alfredo Giner Clara Richart Adrian Pardo Manuel Aranda Carlos E. Larrea Jesus M. Blazquez Daniel Voces Rufino Cabezas Javier Torres

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Development of Novel Electrocatalysts for the Electroreduction of Nitrogen to Ammonia

Roumayssa Amrine José Solla Gullón Vicente Montiel Leguey

a Institute of Electrochemistry, University of Alicante, 03080, Alicante, Spain. [email protected]

Ammonia (NH3) is one of the most widely used chemicals on the planet. As a main feedstock chemical, it is not only indispensable in agriculture, fertilizer and pharmaceutical production, but it also provides a solution to the problems of carbon-free chemical energy for the 1 transportation sector . Nevertheless, the dominant method for industrial scale NH3 synthesis still depends on the Haber–Bosch process which involves the coactivation of hydrogen (H2) and nitrogen (N2) under high temperature and pressure accompanied by large amounts of CO2 emission2. This is why; many researchers are working to find strategic solutions to replace this traditional process. One possible solution may be Nitrogen Electroreduction Reaction (NRR) which is a sustainable and eco-friendly pathway for the synthesis of NH3 using renewable electricity at mild conditions3.

The goal of this PhD thesis deals with the study of the NRR on different nanomaterials based on bismuth (Bi), tin (Sn), and antimony (Sb), as well as the combination of these materials. These nanomaterials will be prepared using well-established methodologies previously used in the research group. The properties of these nanomaterials will be established in terms of activity, selectivity and stability for the electrochemical reduction of nitrogen towards ammonia. All nanomaterials and electrodes will be physicochemically characterized using many different experimental techniques (TEM, SEM, XRD, XPS, among others) which are available in the Research Support Services of the University of Alicante. The prepared nanoparticles will be subsequently used for the fabrication of electrodes. These will be made by air-brushing approaches and using carbon paper substrates. A detailed electrochemical characterization of the nanoparticles and electrodes, also including electrocatalytic experiments to obtain ammonia from nitrogen, will be carried oud using different electrochemical stations available in our research group. The ammonia quantification will be performed using the colorimetric indophenol blue method. Other liquid and gas products will be also analysed by using the analytical unit of the research group (GC, GC-MS, IC and HPLC analyses).

References (1) Wang F, Lv X, Zhu X, et al. Chemical Communications. 2020, 56(14):2107. (2) Wang Z, Zheng K, Liu S, et al. ACS Sustainable Chemistry and Engineering. 2019, 7(13):11754. (3) Zang W, Yang T, Zou H, et al. ACS Catalysis. 2019, 9(11):10166.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

A Study of Polydopamine Thin Film on Glassy Carbon Electrode

Manuel Aranda Ruiz Guadalupe Sánchez Obrero

Departamento de Química Física y T.A., Universidad de Córdoba, Spain, Instituto Universitario de Nanoquímica (IUNAN), Universidad de Córdoba, Spain [email protected]

The formation of polydopamine (PDA) thin films becomes an interesting method to endow with multiple functionality solid–liquid interfaces due to the presence of catechol groups embedded in the film in the polymerization process. PDA is a polymer of great interest due to its excellent adhesive properties and its production is bioinspired in marine mussels behaviour that adhere firmly to various surfaces.

The surface polymerization is really produced by different mechanisms such as self- polymerization of dopamine (DA) or as an alternative, by electrochemical polymerization (e- PDA).1 This electrochemical method exhibits a very appropriate deposition rate, and it is efficient in dopamine control as compared with self-polymerization.

However, e-PDA coatings exhibit structural differences and pathways depending on experimental conditions. Then, substrate polymer coaching may produce a polymeric matrix with high electroactivity due to surface quinone groups and catechol residues. These functional chemical groups are suitable for covalent or electrostatic interactions of biomolecules or organic ad-layers, including for example, secondary reactions with thiols and amines via Michael addition or Schiff reactions2. Therefore, the construction of fixed structure and reproducible properties of a polydopamine thin film is still challenging in most of its applications as biosensors and biomedicine.

In this work, dopamine electrochemical polymerization is studied, using cyclic voltammetry and impedance spectroscopy on a glassy carbon electrode (GCE). The variation of polymerization conditions, such as scan rate, buffer or scan cycles can significantly influence the polymerization mechanism, giving to structural differences on the polymeric matrix. Once the formation of the polydopamine is optimized on the glassy carbon electrode, it is used as a platform to support ω-alkanethiol derivatives as pseudo-self-assembled monolayers and/or biomolecules such as the cofactor pyridoxal 5'-phosphate, a member of the vitamin B6 family.

References

(1) Almeida, L.; Correia, R.; Marta, A.; Squillaci, G.; Morana, A.; Cara, F.; Correia, J.; Viana, A., Applied Surface Science 2019, 480, 979–989 (2) Haeshin Lee, Shara M. Dellatore, William M. Miller, Phillip B. Messersmith. Science 2007, 318, 426.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Vanadium Electrolytes Development for Advanced Flow Batteries

Sabrina Berling,a Enrique García - Quismondo,a and Jesus Palmaa

a Electrochemical Processes Unit, IMDEA Energy, Avda. Ramón de la Sagra 3, 28935, Móstoles, Madrid, Spain [email protected]

Redox Flow Batteries (RFB) are energy storage systems that use electrolytes as charge transport agents. But these electrolytes, typically consistent of vanadium solutions, are not stable in a wide range of temperature and at the same time have thermal properties that can be harnessed to improve their performance in hybrid energy storage systems that integrate RFBs and thermal energy storage technologies, such as geothermal systems.

At high temperatures V(V) ions slowly precipitate from solution, the extent and rate of which being dependent on temperature, vanadium and sulfuric acid concentration as well as the SOC of the electrolyte. In contrast to the V(V) ions, V(II), V(III) and V(IV) ions will precipitate at temperatures below 10ºC at concentrations above 1.6 M in solutions with total sulfate concentration of 5 M. Thus, practical RFB systems operate with electrolyte containing a vanadium concentration between 1.6 and 1.8 M and usually also employ electrolyte cooling and heating systems to maintain the temperature between 15 and 40ºC. This limits the integration of RFB systems in thermal applications that require broad temperature adaptability1– 4, however, a flow battery electrolyte with lower vanadium concentration would allow a wider range of applications to be exploited.

In an effort to enhance the operational temperature range of the VRB, in this thesis it is proposed to develop vanadium electrolytes improved with capacity increase systems through the use of compounds with ability to increase the solubility or enhance the electronic transfer mechanisms. A significant enhancement in the energy density of the VRB is strongly needed to increase the penetration of this type of systems in the market, and with that, their commercialization in the expected terms and volumes. Therefore, the main objectives of this thesis is the development of a new generation of vanadium electrolytes for emerging applications characterized by better performance in wider temperature ranges and their integration in flow cells focusing on the proof of the novel energy storage concept.

References (1) Skyllas-Kazacos, M.; Rychick, M.; Robins, R. All-Vanadium Redox Battery. Pat. US 4786567 1988. (2) Skyllas-Kazacos, M. New All-Vanadium Redox Flow Cell. J. Electrochem. Soc. 1986, 133 (5), 1057. https://doi.org/10.1149/1.2108706. (3) Skyllas-Kazacos, M.; Kazacos, G.; Poon, G.; Verseema, H. Recent Advances with UNSW Vanadium-Based Redox Flow Batteries. Int. J. Energy Res. 2010. https://doi.org/10.1002/er.1658. (4) Parasuraman, A.; Lim, T. M.; Menictas, C.; Skyllas-Kazacos, M. Review of Material Research and Development for Vanadium Redox Flow Battery Applications. Electrochim. Acta 2013, 101, 27–40. https://doi.org/10.1016/j.electacta.2012.09.067.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Electrochemical characterization of bromide and chloride salts of cetyltrimethylammonium on polyoriented gold electrodes.

Jesús Manuel Blázquez Moreno

Teresa Pineda

Department of Physical Chemistry and Applied Thermodynamics, Institute of Fine Chemistry and Nanochemsitry, Universidad de Cordoba, Campus Rabanales, Ed. Marie Curie 2ª Planta, E- 14014 Cordoba, Spain

Presenting author’s email: [email protected]

Cetyltrimethylammonium bromide (CTAB) is a popular member of the halide salts of quaternary ammonium surfactant ions that is widely used as ligand/stabilizer for the seed mediated synthesis of gold nanorods in aqueous solution. This is attributed to the strong affinity of bromide on gold that, once adsorbed on the gold surface, acts as scaffold for the cationic surfactant that constitute the first portion of the known bilayer arrangement that endows high stability of these nanoparticles in aqueous solution.1, 2 It is believed that the preferential adsorption of CTAB on (100) over (111) facets during growth is responsible for the formation of the anisotropic nanoparticles.

To get more insight into the bilayer arrangement of CTAB on gold surfaces, in this work we describe an electrochemical study of the adsorption of CTAB on a polyoriented gold electrode in a neutral medium (c.a., 0.1 M NaF solutions). Cyclic voltammetry has been used to characterize the different process taking place in the double layer region. It has been found that in the presence of low CTAB concentration ( 1 mM; close to the critical micellar concentration) a set of adsorption peaks are observed that show a symmetrical shape with respect to the zero-current axis. However, increasing CTAB concentration, a current spike at around 0 V is observed going to positive values, that has not counterpart in the reverse scan. We have analyzed the influence of scan rate and temperature on the cyclic voltammograms to find out if the electrochemical features correspond to phase transitions. Moreover, an electrochemical impedance spectroscopy study has been made in all the potential range of interest at different temperatures.

Finally, a complementary study by using the chloride salt of cetyltrimethylammonium (CTAC) has been made to compare and evaluate the role of the anion in the adsorption processes.

References.

1. Lohse, S. E.; Murphy, C. J., Chem. Mater. 2013, 25 (8), 1250-1261. 2. del Caño, R.; Gisbert-González, J. M.; González-Rodríguez, J.; Sánchez-Obrero, G.; Madueño, R.; Blázquez, M.; Pineda, T., Nanoscale 2020, 12 (2), 658-668.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Construction of mixed monolayers of 1-decanothiol (DT) and 6-mercaptopurine (6MP) on gold electrode for the control of charge transfers of redox pairs

Rufino Cabezas Monteroa José Manuel Sevilla Suárez de Urbinab

a Departamento de Química Física y Termodinámica Aplicada. Universidad de Córdoba, Córdoba, España b Departamento de Química Física y Termodinámica Aplicada, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, Universidad de Córdoba, Córdoba, España

Presenting author’s email: [email protected]

Mixed SAMs are self-assembling, multi-component monolayers into well-defined 2D molecular structures (1). Among the applications that interest us are the construction of functional surfaces as a resource in nanomaterials and nanomedicine. In particular, mixed SAMs play a role in facilitating the reactivity of atom transfer radical polymerization (ATRP) by increasing the options for charge transfer (2). Self-assembled 1-decanethiol (DT) monolayers strongly block redox probe electron transfers, whereas 6-mercaptopurine (6MP) do not block against the same redox pairs. This represents an opportunity to characterize mixed monolayers of both thiols and, with it, to optimize the conditions that make compatible the strong DT coating on the metal substrate and an adequate electroactivity. For the characterization of these SAMs and the mixed SAMs, cyclic voltammograms have been recorded at different modification times in the reductive desorption potentials zone. The study -3/-4 of the integrity of the monolayer and the blocking effect with the Fe(CN)6 redox couple has been carried out by means of cyclic voltammetry and impedance. Contact angle experiments have also been performed. The experiments to form the SAMs were carried out with a modification time of one hour and under thermodynamic conditions (overnight, 24 hours). The whole of strategies and results obtained can serve as a base tool in e-ATRP (electrochemically mediated ATRP).

References (1) Gonzalez-Granados, Z.; Sanchez-Obrero, G.; Madueno, R.; Sevilla, J. M.; Blazquez, M.; Pineda, T., J. Phys. Chem. C 2013, 117 (46), 24307-24316. (2) Zoppe, J. O.; Ataman, N. C.; Mocny, P.; Wang, J.; Moraes, J.; Klok, H. A. Chem. Rev. 2017, 117 (3), 1105–1318.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Cycle Stability in Aqueous Organic Flow Batteries

Koray Cavusoglu,a Álvaro Colina and Edgar Ventosa,a

a Department of Chemistry, Faculty of Science, University of Burgos Plaza Misael Bañuelo s/n E-0900, Spain Presenting author’s email: [email protected]

The long-desired transition to a sustainable and environmentally friendly energy model requires large-scale implementation of energy generated from renewable sources into the grid. To achieve this, efficient energy storage systems (EESs) play an essential role due to the intermittent nature of resources sources, such as wind and solar radiation. Among various EESs, batteries offer high energy density and efficiency at moderate cost. While Li-ion batteries are the power source of choice for electric vehicle due to their high specific energy, redox flow batteries (RFBs), in which electroactive species are stored in external reservoirs (Figure 1), are more suitable for stationary energy storage application due to their independent scalability of power and energy. The all-vanadium redox flow battery represents the state-of-the-art RFB. However, this element is considered to be a critical raw material for both the USA and EU, which has triggered interest Figure 1. Scheme of a redox flow battery. in finding suitable candidates to replace vanadium. Reproduced with permission from [1] In this context, aqueous redox flow battery based on organic and Earth-abundant organometallic electroactive species has gain momentum as a sustainable solution for large-scale stationary energy storage[1]. A variety of species has been shown to fulfil the requirements to be used in redox flow batteries. Besides the sustainability of organic compounds, these materials offer a secondary major advantage: easy tunability of their properties (e.g. redox potential and solubility) by slight modification of their structure. As a result, aqueous organic redox flow batteries (AORFBs) are one of the most promising EESs for large-scale stationary energy storage[1]. In this Master Thesis, the cycle stability of AORFBs is put under the spotlight as cyclability together with levelized cost are the two main factors for stationary energy storage as indicated by European Strategic Energy Technology Plan for Energy. The main sources for energy storage capacity decay are discussed, identifying that the influence of irreversible side reactions as one of the main sources. This factor is investigated in detail using the state-of-the-art AORFBs chemistry. An innovative strategy is proposed and validated for preventing energy storage capacity decay due to these side reactions.

Reference (1) Sánchez-Díez, E.; Ventosa, E.; Guarnieri, M.; Trovò, A.; Flox, C.; Marcilla, R.; Soavi, F.; Mazur, P.; Aranzabe, E.; Ferret, R. Journal of Power Sources, 2021, 481, 228804.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Gel Polymer Electrolyte for Energy Storage System

Diana Elena Ciurduc,a Rebeca Marcilla,a

a Electrochemical Processes Unit, IMDEA Energy, Avenida Ramón de la Sagra 3, 28935 Móstoles, Madrid, Spain Presenting author’s email: [email protected]

An energy storage device is a combination of electrodes and an electrolyte in term of their processing, structures and properties. The electrolyte is one of the key components, which act as the ion transport pathway. Liquid electrolytes are widely used in lithium-ion batteries because of their high ionic conductivity, but safety problems are related with lithium metal anodes such as the leakage of electrolyte, flammability of the organic solvents and the formation of dendrites. 1 In order to avoid these drawbacks, polymer electrolytes have been considered due to their wide electrochemical window, good thermal and reduction of the leakage. For this reason, by combining the advantages of both the liquid and solid electrolytes, the gel polymer electrolyte shows high ionic conductivity, good interfacial and mechanical properties. 2 Recently, highly concentrated nonaqueous electrolytes have been receiving intense attention due to the fact that the amount of free solvent molecules is dramatically decreased and the interactions between ions and solvent increases, forming a peculiar 3D solution structure. This lack of free solvent molecules, slows down the corrosion of the electrode material and concentrated electrolytes can passivate the graphite anode or Al cathode current collector 3 without the use of EC and LiPF6, respectively. The strategy presented here is to design gel polymer electrolytes based on PVDF-HFP porous matrix where the commonly used organic-based electrolytes are substituted by superconcentrated electrolytes with a two-fold objective: i) to avoid the leakage of liquid by developing self-standing gel polymer membranes with adequate mechanical properties and ii) to improve the electrochemical stability and safety of conventional gel electrolytes by using superconcentrated electrolytes. In particular, concentrated solutions of LiTFSI in DMC/FEC are used in combination with PVDF-HFP porous polymer matrix. The physicochemical and electrochemical properties of GPEs with different electrolyte compositions were carefully studied. GPE with optimized composition was found to prevent aluminium corrosion and used as gel electrolyte in lithium-metal cells with LFP and NMC111 as cathodes. Both batteries exhibited high values of specific capacity (147 mAh g-1 and 160mAh g-1 at 0.1 mA cm-2) and good rate capability (88% and 84%) at room temperature. 4 In the next phase, our intention is to use the strategy of molecular crowing already applied to an aqueous Li-ion battery and transfer it to an aqueous Zn-ion system. The molecular crowding is a low cost, and eco-friendly aqueous electrolyte with a wide voltage window that allows to achieve safe, high-energy and sustainable systems. This is possible by confining the water molecules in a crowding agent (PEG) network through hydrogen bonding. 5 References (1) Xu, W.; Wang, J.; et al . Energy Environ. Sci. 2014, 7 (2), 513–537. (2) Zhu, M.; Wu, J.; et al. J. Energy Chem. 2019, 37, 126–142. (3) Yamada, Y.; Wang, J.; et al. Nat. Energy 2019, 4 (4), 269–280. (4) Ciurduc, D.E.; Boaretto, N.; et al. Journal of Power Sources, under revision. (5) Xie, J.; Liang, Z.; et al. Nat. Mater. 2020, 19 (9), 1006–1011.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Study of carbon nanostructures. Synthesis, structural characterization and applications

Ángela Fernández Merino Teresa Pineda

Departamento Química Física y Termodinámica Aplicada, Instituto de Química Fina y Nanoquímica, Universidad de Córdoba, Ed. Marie Curie, 2ª Planta, Campus de Rabanales, 14014 Córdoba, España.

email: [email protected]

Carbon dots (CDs) have emerged as promising alternatives to semiconductor quantum dots due to its low toxicity, tunable fluorescence and easy production.1 CDs are generally defined as a quasi – 0D carbon based materials with sizes below 20 nm and they are classified into graphene quantum dots (GQDs), carbon quantum dots (CQDs), and carbonized polymer dots (CPDs) according to their different formation strategy, nanostructures and properties. GQDs are composed of one monolayer or multilayer graphitic structures with different chemical groups on their surface or within the layer defects, and they are anisotropic. In contrast, CQDs and CPDs are typically spherical and, whereas CQDs exhibit multilayer graphite structure connected to surface functional groups with intrinsic luminescence and quantum confinement size effect, the CPDs are aggregated or crosslinked carbonized polymer nanostructures that also show luminescence. The CDs optical properties are being object of many research in the last decade as they emit in all the visible spectral range (from blue to red regions) that make possible its applications as sensors, in energy, catalysis, within other fields.2 Although there are some reports applying CDs to electrocatalysis, pseudo- and supercapacitors and batteries, not many electrochemical studies are reported. The main object of this project is to synthesize CDs with precise emission properties, either in the blue, green or red spectral regions. To obtain them it will be necessary to design synthesis methods that allow doping of the carbon structures mainly with O, N and S atoms to enhance the emission quantum yield and to regulate the band gap. The purification methods that allow the separation of the CDs by size and chemical nature will be assayed. The intrinsic electrochemical properties of these CDs with specific properties first based on its luminescence properties, as well as some electrochemical applications will be studied. Different electrochemical techniques such as voltammetry and electrochemical impedance spectroscopy will be used together with fluorescence spectroscopy (stationary and non-stationary) and other characterization techniques currently used for nanomaterials.

Acknowledgements: We thank the Ministerio de Ciencia e Innovación (Project RED2018-102412-T Network of Excellence Electrochemical Sensors and Biosensors), Junta de Andalucía and Universidad de Cordoba (UCO- FEDER-2018: ref. 1265074-2B and Plan Propio, SUBMOD. 1.2. P.P. 2019). References. 1. Du, X.-Y.; Wang, C.-F.; Wu, G.; Chen, S., Angew. Chem. Int. Ed. 2021, 60 (16), 8585- 8595. 2. Liu, J.; Li, R.; Yang, B., ACS Cent. Sci. 2020, 6 (12), 2179-2195.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Study of the Evolution of FeNxCy and Fe3C Species in Fe/N/C Catalysts During the Oxygen Reduction Reaction in Acid and Alkaline Electrolyte

Álvaro Garcíaa, Laura Pascualb, Pilar Ferrer c, Diego Gianolio c, Georg Held c, David C. Grinter c, Miguel A. Peña a, María Retuerto a, Sergio Rojas a, a Grupo de Energía y Química Sostenibles, Instituto de Catálisis y Petroleoquímica, CSIC Marie Curie 2, 28049, Madrid, Spain. b Instituto de Catálisis y Petroleoquímica, CSIC, Marie Curie 2, 28049, Madrid, Spain. c Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK. Presenting author’s email: [email protected]

Fe/N/C catalysts are usually synthesized by thermal treatment in inert and/or NH3 atmospheres of precursors containing C, N and Fe atoms in different ratios. Whereas Fe/N/C catalysts possess high ORR activity, a major issue is catalyst durability. In this work, we assess the durability of Fe/N/C catalyst, based on the polymerization of 1,3 dicyanobenzene [1], by a thorough characterization of the fresh and used catalyst by electrochemical tests, advanced TEM studies and X-ray adsorption. We perform an exhaustive study of the changes observed during the ORR reaction in both media over the Fe species inside the catalyst. In order to a better understanding of what happen to different types of active sites during ORR we carry a specific accelerated stress test (AST) in O2 saturated electrolyte. The samples were deposited onto a TEM grid and were examined by TEM following an identical location (I-L) [2] study before and after the AST. To analyze stability of active sites X-ray absorption spectroscopy also was made of the catalyst after ASTs at same conditions. NEXAFS reveals the presence of two groups of (Fe)NxCy ensembles, namely (Fe)Nx-pyridinic and (Fe)Nx-pyrrolic. Identical- Location TEM study verifies which species are the most prone to disappear and dissolve in each electrolyte, and for the contrary, which particles remain in the structure providing durability to the catalyst. XAS study reveals that (Fe)Nx-pyrrolic moieties are the main ones in the fresh catalysts, but (Fe)Nx-pyridinic groups are more stable after the ORR.

References

[1] P. Kuhn, M. Antonietti, A. Thomas, Porous, Covalent Triazine-Based Frameworks Prepared by Ionothermal Synthesis, Angew. Chemie Int. Ed. 47 (2008) 3450–3453. https://doi.org/10.1002/anie.200705710. [2] F.J. Perez-Alonso, C.F. Elkjær, S.S. Shim, B.L. Abrams, I.E.L. Stephens, I. Chorkendorff, Identical locations transmission electron microscopy study of Pt/C electrocatalyst degradation during oxygen reduction reaction, J. Power Sources. 196 (2011) 6085–6091. https://doi.org/https://doi.org/10.1016/j.jpowsour.2011.03.064.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Photoelectrochemical study of BiFeO3 thin films

Alfredo Giner Requena Teresa Lana Villarreal Institut Universitari d’Electroquímica i Departament de Química Física, Universitat d’Alacant, Apartat 99, 03080 Alacant (Spain) Presenting author’s email: [email protected]

The increasing global energy demand and the concomitant contamination made imperative to find alternatives to traditional energy sources such as fossil fuels. Storing energy from sunlight, just as nature accomplishes photosynthesis, is a very attractive alternative to face this problem. Solar energy can be converted into chemical energy generating new atomic bonds. In this context, hydrogen generation from the dissociation of water, process known as “water splitting”, is of particular interest.

The use of transition metal ternary oxides, such as BiFeO3 have been proposed in the literature as good candidates to perform this process. BiFeO3 is of great interest due to its ferroelectric properties, but its band gap (2.2 eV), band position, stability, low cost and low toxicity make it suitable for water splitting. Furthermore, this material can behave both as a photoanode and as a photocathode. Its practical used is limited by the fast recombination of the photogenerated charges.

This work focuses on the preparation, modification and photoelectrochemical study of BiFeO3 thin films. These electrodes have been modified by two different procedures:(i) by doping with metal cations (Mg and Ca) and (ii) by generating p-n junctions with n-type semiconductors (Bi2O3, TiO2).

Techniques such as XRD, SEM or XPS have been used for structural and compositional characterization, whereas cyclic voltammetry and linear voltammetry in the dark and under illumination have been used as the main electrochemical characterization techniques. The effect of the modifications on the band gap, flat band potential, photocurrent onset and magnitude have been studied. The modification of BiFeO3 with dopants mainly induces a diminution of the photocurrent, while the generation of a p-n junction induces a considerable increase of the photocurrent.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

The role of lithium, perchlorate and water during electrochemical processes in poly(3,4-ethylenedioxythiophene) films in 𝑳𝒊𝑪𝒍𝑶𝟒 aqueous solutions.

Esteban Guillén Bas,a José Juan García Jareño,b

a Departament de Química Física, Universitat de València. C/ Dr. Moliner, 50, 46100, Burjassot, València, Spain b Departament de Química Física, Universitat de València. C/ Dr. Moliner, 50, 46100, Burjassot, València, Spain Presenting author’s email: [email protected]

Thin films of poly(3,4-ethylendioxythiophene) (PEDOT) were electrochemically deposited on gold electrodes in aqueous media. The role of perchlorate, lithium, and water during the charge/discharge of PEDOT films was investigated by cyclic voltammetry together with EQCM, vis−NIR spectroscopy, and acoustic impedance, also by means of ac-electrogravimetry in a 0.1 M 𝐿𝑖𝐶𝑙𝑂 aqueous solutions. In this way, it has been possible to correlate the electrical, mass, color and electromechanical properties changes during the electrochemical reactions of this polymer. Both, hydrated lithium cations and perchlorate anions can act as counterions during the electrochemical reactions, however, at the more positive potentials anions are the preferred ions while at the more negative potentials the relative participation of cations increases. A secondary electrochemical reaction appears in aqueous solutions at potentials near 0.38 V against the Ag|AgCl|KCl(sat) reference electrode and it is neither associated with mass changes nor with spectroscopic changes of the PEDOT. Viscoelastic properties of the film change also with the applied potential and this change is mainly observed at the more negative potentials due to the exchange of highly hydrated 𝐿𝑖 cations.

References (ACS format) (1) A.R. Hillman, S.J. Daisley, S. Bruckenstein, Electrochemistry Communications. 2007, 9, 1316–1322. (2) A.R. Hillman, S.J. Daisley, S. Bruckenstein, Physical Chemistry Chemical Physics. 2007, 9, 2379–2388. (3) J. Agrisuelas, J.J. García-Jareño, D. Gimenez-Romero, F. Vicente, The Journal of Physical Chemistry C. 2009, 113, 8430-8437. (4) J. Agrisuelas, J.J. García-Jareño, D. Gimenez-Romero, F. Vicente. The Journal of Physical Chemistry C. 2009, 113, 8438-8446. (5) J. Agrisuelas, C. Gabrielli, J.J. García-Jareño, H. Perrot, O. Sel, F. Vicente. Electrochimica Acta. 2015, 176, 1454-1463.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Syngas Production from the Electrochemical Reduction of CO2

Carlos Larrea Castro,a Dra. Pilar Ocón Esteban,a Dr. Juan Ramón Avilés Moreno,a

a Facultad de Ciencias, Ciudad Universitaria de Cantoblanco, Madrid, Spain Presenting author’s email: [email protected]

The increasing concentration of carbon dioxide (CO2) in the atmosphere has prompted the search for innovative techniques for recycling CO2. The electrochemical reduction of CO2 (CO2RR) offers a potentially scalable method for converting this gas into value-added chemicals and fuels. Specifically, CO2 can be reduced to CO which along with H2 forms syngas, a versatile product which is the main precursor in methanol synthesis or can be turned into long- chain hydrocarbons through the Fischer-Tropsch process, enabling the storage of electric energy as chemical energy. This presentation will look into the CO2RR process from concentrated bicarbonate electrolyte. This mode of CO2RR provides potential solutions to the most challenging problems of working with a purely gaseous CO2 feed, and a more simplified path to integrate the CO2 capture process. Our latest research has focused on the effect of the anolyte’s pH and membrane polarity on CO2RR in a zero-gap MEA flow cell configuration. The parameters evaluated include selectivity, cell potential, and residual CO2 concentration. In addition, the effects of temperature on CO2RR will be presented. Finally, this presentation will discuss the current state of development of this technology and its outlook.

References

(1) Li, T.; Lees, E. W.; Goldman, M.; Salvatore, D. A.; Weekes, D. M.; Berlinguette, C. P. Electrolytic Conversion of Bicarbonate into CO in a Flow Cell. Joule 2019, 3 (6), 1487–1497. (2) Li, Y. C.; Lee, G.; Yuan, T.; Wang, Y.; Nam, D.-H.; Wang, Z.; de Arquer, F. P.; Lum, Y.; Dinh, C.-T.; Voznyy, O.; Sargent, E. H. CO2 Electroreduction from Carbonate Electrolyte. ACS Energy Lett. 2019, 4 (6), 1427–1431. (3) Zhang, Z.; Melo, L.; Jansonius, R. P.; Habibzadeh, F.; Grant, E. R.; Berlinguette, C. P. PH Matters When Reducing CO2 in an Electrochemical Flow Cell. ACS Energy Lett. 2020, 5 (10), 3101–3107.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Determination of free Zn concentration in biological media with the AGNES technique (Absence of Gradients and Nernstian Equilibrium Stripping).

Lucia López-Solis,a) Encarna Companys,a) and Josep Galcerana) a) Dep. Química, Universitat de Lleida, and AGROTECNIO, Rovira Roure 191, 25198, Lleida, Spain Presenting author e-mail: [email protected]

Amongst the electroanalytical techniques, AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) technique has the specificity of directly quantifying the free ion concentration [1]. AGNES technique is based on the accumulation of the reduced form of the analyte (Zn0) in the amalgam until Nernstian equilibrium is met at the electrode surface. The accumulated amount, which is proportional to the free concentration of analyte in the sample, can, then, be quantified [2].

This research project focuses on the measurement of free zinc in biological systems, since it is known that this metal participates as a cofactor in many enzymatic processes [3], that both an excess and a deficiency can cause functional imbalances in a system and that, so far, in the recent literature there are no reports of an accurate value of this fraction, because it is found in very small amounts and quantifying it would be a great contribution. Therefore, a challenge of this project will be to reach intracellular levels of free Zn of the picomolar order.

In preliminary experiments, the measurements with the Hanging Mercury Drop Electrode in the mixture 600 µmol L-1 BSA (Bovine Serum Albumin) + 20 µmol L-1 Zn did not provide accurate values due to electrodic adsorption. Therefore, we implemented the use of the Rotating Disc Electrode with a deposited Thin Mercuy Film and with Nafion® coating [4], finding a reproducible value of [Zn2+] ≈ 2.68 nmol L-1. Finally, it has been possible to quantify the free fraction of Zn2+ in the biological medium FBS (Fetal Bovine Serum), finding a value of [Zn2+] ≈ 0.25 nmol L-1.

[1] Galceran, J.;Companys, E.; Puy, J.; Cecilia, J.; Garces, J. Journal of Electroanalytical Chemistry. 2004, 566, 95-109.

[2] Galceran, J.; Lao, M.; David, C.; Companys, E.; Castro-Rey, C.; Salvador, J.;Puy, J. Journal of Electroanalytical Chemistry. 2014. 722-723, 110-118.

[3] Prasad, A.S. Journal of trace Elements in Medicine and Biology. 2014. 28, 357-363.

[4] Vidal, J.; Cepria, G.; Castillo, J. Analytica Chimica Acta. 1992. 259, 129-138.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Design and development of instrumentation for open-source chemical analysis: application to the analysis of environmental and health parameters.

A.N. Martín-Gómez Departamento de Ingeniería Química, Química Física y Ciencia de los Materiales, Universidad de Huelva, 21071 Huelva, Spain Presenting author’s email: [email protected] A large number of analytical methods based on flow-based systems (FIA: Flow Injection Analysis) and derivatives thereof are currently available. Mainly due to their capacity for process automation, a remarkable reagent volume reduction leading to a significant reduction of waste, and a general improvement of parameters of analytical interest such as greater reproducibility, higher yields and miniaturization capability of a robust analytical device1. However, the costs associated with the acquisition of analytical instrumentation are considerably high, mainly affecting developing countries. In this regard, the aim of this project is the design and manufacturing of an automatic analytical device, OSHW based (Open Source Hardware). This allows anyone to build a similar setting of physical equipment from scratch by reusing, repairing, refurbishing remanufacturing and recycling components, mixed with the use of 3D printing technologies, since the assembly diagrams and specifications are freely available. The system will consist of the following parts: -An automated fluid drive system -An injection valve with the possibility of remote control. -A set of detectors (amperometric, potentiometric, optical, etc.). -Software to configure the equipment, to control the experiment and to acquire and process the data. Further testing and application of this system to the analysis of chemical parameters in different areas, such as medical analysis or water treatment, is also part of the objective of this thesis.

References

(1) Ruzicka, J.; Hansen, E. H. Flow Injection Analysis; John Wiley & Sons Inc: New York, United States, 1988.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Oxidación electroquímica del glicerol en medio alcalino sobre nanomateriales de Pt-Rh

Adrián Pardo Jara José Solla Gullón

Instituto de Electroquímica, Universidad de Alicante, Apdo 99, 03080 Alicante, España [email protected]

La necesidad de fuentes de energía más ecológicas ha llevado, entre otras posibilidades, a aumentar en todo el mundo la producción de biodiesel como sustituto renovable del diésel. Sin embargo, esta producción de biodiesel, mayoritariamente mediante la transesterificación de triglicéridos, lleva consigo la co-generación de grandes cantidades de glicerol (1,2,3- propanotriol) como principal subproducto de la reacción. De esta forma, y a pesar de que el glicerol puede ser empleado en diferentes industrias como la alimentaria, la farmacéutica y la cosmética, éste se está generando en cantidades desmesuradas como subproducto mayoritario del proceso de fabricación de biodiésel. De esta forma, es necesaria la búsqueda de soluciones para dar salida a este subproducto ya que está causando un gran impacto a nivel económico y medioambiental en la biorefinería industrial. De entre los posibles usos del glicerol, su empleo en sistemas electroquímicos es especialmente interesante ya que podría utilizarse i) para la generación de productos de valor añadido provenientes también de su proceso de electrooxidación y ii) como combustible para generación de energía mediante su oxidación electroquímica1,2. Con estas dos diferentes perspectivas, la literatura está mostrando un creciente interés en el estudio del proceso de electrooxidación de glicerol especialmente en metales nobles3,4. En el presente trabajo se pretende estudiar dicha reacción mediante nanocatalizadores de platino y rodio. Para ello se han sintetizado nanopartículas de composición variable (Pt, Pt75Rh25, Pt50Rh50, Pt25Rh75 y Rh) con las que se han preparado electrodos que han sido caracterizados electroquímicamente y utilizados para el proceso de electrooxidación de glicerol en medio alcalino. La distribución de productos generados en el proceso de electrooxidación se glicerol ha sido analizada mediante medidas de HPLC. Los resultados obtenidos permiten visualizar cómo varía el mecanismo de la reacción por efecto de la composición atómica de los diferentes nanocatalizadores.

References:

(1) Dodekatos, G.; Schünemann, S.; Tüysüz, H. Recent Advances in Thermo‑, Photo‑, and Electrocatalytic Glycerol Oxidation, ACS Catal. 2018, 8, 6301. (2) Martins, C. A.; Fernández, P. S.; Camara, G. A. Alternative Uses for Biodiesel Byproduct: Glycerol as Source of Energy and High Valuable Chemicals in Increased Biodiesel Efficiency, M. Trindade (Ed), Springer International Publishing, 2018, Chapter 7, 159. (3) Coutanceau, C.; Baranton, S.; Kouamé, R. S. B. Selective Electrooxidation of Glycerol into Value-Added Chemicals: A Short Overview. Front. Chem. 2019, 7, 1. (4) Fan, L.; Liu, B.; Liu, X.; Senthilkumar, N.; Wang, G.; Wen, Z. Recent Progress in Electrocatalytic Glycerol Oxidation. Energy Technol. 2021, 9 (2), 2000804.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Electrochemical carbon-bromide bond cleavage of spyropiran switches for CO2 capture in polar aprotic solvents and ionic liquids

Clara Richart López, Gonzalo Guirado López

Departament de Química, Universitat Autònoma de Barcelona, 08193- Bellaterra (Barcelona), 08193, Spain.

Presenting author’s email: [email protected]

This communication deals with carbon capture and utilization to synthetize high-added chemicals using CO2 as a C1-organic building block for C-C bond formation. Our study focuses on the electrocarboxylation of 1,3,3-trimethylindolino-6'-bromobenzopyrylospiran (1) switch. Prior to the electrocarboxylation process, the electrochemical reduction mechanism of 1 and CO2 is disclosed in polar aprotic solvents and ionic liquids (ILs) using three different cathodes (glassy carbon, silver and copper) under nitrogen atmosphere [1-3] . Once, the role of the cathode and solvent, in the reduction carbon-bromide bond cleavage is understood, carboxylated spyropiran derivatives can be synthetizing in high yield (c.a. 90 %) and conversion rates (c.a. 90%) through an electrocarboxylation process using CO2, silver cathode and either polar aprotic solvents or ILs. The "green" efficient route described in the current work would open a new sustainable strategy for designing and building “smart” surfaces with switchable physical properties. [4]

Keywords: Electrocarboxylation, electrochemistry, reduction, capture, carbon dioxide, spiropyran, n, n-dimethylformamide, ionic liquid.

References (1) Mena, S.; Rivas, E.; Richart, C.; Gallardo, I.; Faraudo, J.; Shaw S. K.; Guirado, G. J. Electroanal. Chem. 2021, in press. (2) Mena, S.; Sanchez, J.; Guirado, G. RSC Adv., 2019, 9, 15115. (3) Mena, S.; Santiago, S.; Gallardo, I.; Guirado, G. Chemosphere, 2020, 245, 125557. (4) Santiago, S.; Giménez-Gomez, P.; Muñoz-Berbel, X.; Hernando, J.; Guirado, G. ACS App. Mat. & Interfaces, 2021, in press.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Dynamic and equilibrium metal speciation in aquatic environmental systems elucidated with emerging techniques.

Kevin Rosales-Segoviaa, Josep Galceran and Encarna Companysa,

a Dep. Química, Universitat de Lleida, and AGROTECNIO-CERCA, Rovira Roure 191, 25198, Lleida, Spain Presenting author’s email: [email protected]

The hegemonic paradigms of ecotoxicology postulate that some available fraction of a specific pollutant is better correlated with its impact than its total amount. Therefore, its necessary to take into account the speciation of the pollutant, i.e. how the total amount of pollutant is distributed among chemical forms that have different physicochemical and biochemical properties. In the case of the Free Ion Activity Model, FIAM [1] or the Biotic Ligand Model, BLM [2], the key role is played by the free concentration of the metal ion.

Electroanalytical techniques have always played an important role in environmental monitoring. Their in situ measurement possibilities, low cost, low detection limits and rapid analysis are some of their strengths. One typical weakness is the difficulty in interpreting the measurements. On the other hand, there are no techniques indicated for all matrices and for all analytes. Rather, each technique provides complementary information that must be judiciously integrated into a sound interpretative framework to obtain a more representative picture of the analysed medium.

This work develops and applies primarily (but not exclusively) two complementary techniques: Donnan Membrane Technique (DMT) and Absence of Gradients and Nernstian Equilibrium Stripping (AGNES). AGNES is an electroanalytical technique specifically designed to measure free metal ion concentrations for amalgamating elements such as Zn, Cd, Pb and Sn or In [3]. The Donnan Membrane Technique (DMT) is a passive sampler that provides (when using a cation exchange membrane) free cation concentrations [4]. Its principle is the equilibrium between the target analyte in the sample solution (or donor) and in a synthetic solution (acceptor), which are separated from each other by an ion exchange membrane [5].

References: [1] Anderson, M., Morel, F., & Guillard, R. (1978). Nature, 276, 70-71. [2] Paquin, P., Gorsuch, J., Apte, S., Batley, G., Bowles, K., Campbell, P. . . . Stubblefield, W. Comp. Biochem Physiol C (2002), 133, 3-35. [3] E. Companys, J. Galceran, J.-P. Pinheiro, J. Puy, P. Salaün, Current Opinion in Electrochemistry 2017, 3(1), 144-162.

[4] Chito, D., Weng, L., Galceran, J., Companys, E., Puy, J., van Riemsdijk, W., & van Leeuwen, H.P. Science of the total environment (2012), 421, 238-244. [5] Weng, L., Temminghoff, J., Lofts, S., Tipping, E., & van Riemsdijk, W. Environmental Science and Technology (2002), 36 (22), 4804-4810.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Evaluation of the most prominent parameters of Ion Exchange Membranes. Membrane modification for Energy storage application.

Ivan Salmeron-Sànchez,a Juan Ramón Avilés-Moreno, Pilar Ocón,b

a Dto. Química Física Aplicada, Universidad Autónoma de Madrid (UAM), Madrid, Spain [email protected]

Redox Flow Batteries (RFBs) are considered the best option to store electricity from medium to large scale applications, performing in a sustainable and highly efficient way. Many prototypes have been developed such as all-vanadium that has been extensively studied.1,2 One of the key components of these systems is the ion exchange membrane (cationic and/or anionic). The function of the membrane is to prevent cross mixing of the positive and the negative electrolytes and the short-circuit of the two half cells. Additionally, they should offer good ionic conductivity and present an economic viability as an alternative to the most widely used membrane, the Nafion® membrane. Therefore, membrane modifications3 is an attractive pathway to pursuit in order to avoid the battery capacity decay. These methods are able to produce a thin and fine distributed layer and also to modify the chemical structure of the surface. The new layer can be adsorbed, deposited, or chemically bonded on a membrane surface. By using these methods, membrane properties can be improved. In this work, the modification strategy performed is the chemical in situ polymerization of pyrrole monomer which hinders the permeation of the active species by filling the pores and cavities of the pristine membrane. Physicochemical properties of ion exchange membranes (IEMs) are rather important to forsee the performance of a RFB and how the processes to complete the electric circuit take place.4-6 Membrane characterization includes the comprehensive studies on equilibrium and physical-mechanical properties (ion exchange capacity, water content, ion conductivity and mechanical properties); those on transport properties (transport number of ions and permselectivity) and structural characteristics (FTIR, DR and SEM). The objectives of this work is (1) to perform a membrane modification looking forward decreasing the crossover phenomena of the redox active species, (2) to summarize the results of experimental studies on physicochemical characteristics and transport properties of IEMs, and (3) to find out some of the important factors involved in ion transfer mechanisms.

References (1) Nam, T.; Doan, L.; Hoang, T. K. A.; Chen, P. RSC Adv. 2015, 5, 72805. (2) Lourenssen, K.; Williams, J.; Ahmadpour, F.; Clemmer, R.; Tasnim, S. J. Energy Storage. 2019, 25, 100844. (3) G. Gohil; V. Binsu, V. Shahi. J. Memb. Sci. 2006, 280, 210-218. (4) Small, L. J.; III, H. D. P.; Anderson, T. M. J. Electrochem Soc. 2019, 166 (12), A2536. (5) L. X. Tuan. J. Colloid Interface Sci. 2008, 325, 215-222 (6) N. P. Berezina; N. A. Kononenko; O. A. Dyomina, N. P. Gnusin. Adv. Colloid Interface Sci. 2008, 139, 3-28

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

2D nanomaterials for Energy Store

Laura Sierra,a Pilar Ocón,a a Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Madrid, España [email protected]

The energy demands together with the tendency to end with the emissions responsible of the climate change has focused the attention on the research of novel materials for be used in energy store applications. In this sense 2D materials are emerge as special candidates because they present good properties like chemical and mechanical stability, and they have applications for optical and electronic devices. Our research was focused on the application of two types of 2D materials, 2D α-Ge as promising material for anode in Lithium-ion batteries and Covalent Organic Framework (COF) as high areal electrodes for Double Layer Capacitors applications. The main interest in theses material is about their properties. Ge as anode for Lithium-ion batteries has interest because it has a good theoretical capacity (1600 mAh g-1) higher than anodes of graphite (372 mAh g-1).1,2 We present a simple method to obtain 2D- α Ge particles with a ball milling process since bulk α-Ge crystals to be used as anode material. The electrochemical performance of 2D α-Ge as anode in semi-cells was evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The anode was performance by slurry method with 80:10:10 of 2D α-Ge, carboxy methyl cellulose as binder and Vapor Grown Carbon Fibers as conductivity agent. Coin semi-cell 2032 was conformed with Li metal as reference and counter electrode and 2D α-Ge as working electrode with 1M LiPF6 ethylene carbonate and diethyl carbonate (EC:DEC) (1/1 V% ) and 5% Vinyl carbonate (VC) as electrolyte. We study different amounts of 2D α-Ge (1, 2, 5 and 10 mg/cm2) as active electrode material and we obtain the best performance with a specific capacity of 1630 mAh g-1, and good stability with values of 700 mAh g-1 after 100 cycles a constant current of 0.5C with electrode load of 1 mg/cm2. On the other hand, we study other 2D material, COF as high capacitive double layer capacitors.3,4 We propose an Ultralight Aerogel based on COF structure as good candidate of electrode material because it has a high surface area 1146 m2 g-1. We study two type of Ultralight Aerogel COF structures with three different electrolytes (H2SO4 1M, KOH 6M and TBAPF6 0.25M in acetonitrile) to analyses the behavior in each medium. The electrochemical performance was evaluated with Swagelok type cell. We conformed a symmetric double layer capacitor with an electrode composition of 70% Ultralight Aerogel COF and 30% Carbon super P, the solid mixing was pressed 2 Ton for five minutes to conform a membrane with 8 mm of diameter and 90 µm of thickness. The results show a good performance with a good stability higher than 95% of capacitance retention after 10,000 cycles at 0.1 A/g for all electrolytes. References: (1) Koo, J.; Peak, S. Nanomaterials 2021, 11, 319. (2) Liu,Y ; Zhang, S. ChemElectroChem 2014, 1, 706-713 (3) Yusran, I. Li, X. Adv. Mater 2020, 32, 1907289 (4) Wu, Y. Awaga, K. ACS Appl. Mater. Interfaces 2019, 22, 7661-7665

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Catalytic activity of Ru complexes leftovers, towards the ORR and OER reactions

J. Torres Escalona,a A. J. Fernandez Romero,a

a Grupo de Materiales Avanzados para la Producción y Almacenamiento de Energía, Universidad Politécnica de Cartagena, Campus de Alfonso XIII, Cartagena. (Spain) Presenting author’s email: [email protected]

Electrochemical storage technologies, such as batteries, are among the key energy storage devices for the next generation of electronics and green vehicles. Among them, metal‐air batteries hold very interesting properties for future energy applications. They offer the highest theoretical energy density, however, reliable rechargeable metal-air batteries remain a challenge. Rechargeable Metal-air battery performance relies on the ORR an OER at the air electrode; therefore, improving the activity and stability of bifunctional catalysts for both reactions, ORR and OER, is necessary. Thus, new materials are tested to be used as bifunctional catalysts for both, ORR and OER. On the other hand, the development of green, sustainable and economical processes, e.g., recycling of noble metals from its wastes to preserve environment and prevent 0.3 exhaustion of natural sources, 0.2 have impelled us to find a 0.1 possible use for the leftovers of 0.0 Ru coordination complexes1. -0.1

In this communication the ) 2 potential use as catalysts for -2

ORR and OER of tunable- N -4 2 composition materials I (mA/cm 000 RPM 100 RPM Ru/RuO2 and Ru/RuO2 200 RPM -6 400 RPM 900 RPM /RuP3O9, obtained from 1600 RPM 2500 RPM thermal decomposition -8 4000 RPM of RuCl3⋅H2O and selected 6400 RPM complexes [RuCl2(p-cymene)]2 -10 and [RuCl2(PPh3)3], were -1.0 -0.8 -0.6 -0.4 -0.2 0.0 Ewe (V vs. Hg/HgO) studied using the RRDE Figure 1: Linear sweep curves obtained with a RRDE for Ru- technique. Finally, these based material from RuCl3∙H2O. Scan rate 50 mV/s in 0,1M materials were employed in the KOH. Rotating speeds are included. air electrode in PVA-KOH- based zinc-air batteries2.

References. (1) Pérez, J.; Serrano, J. L.; Sánchez, G.; Lozano, P.; da Silva, I.; Alcolea, A., ChemistrySelect 2019, 4 (28), 8365–8371. https://doi.org/10.1002/slct.201901392. (2) Santos, F.; Tafur, J. P.; Abad, J.; Fernández Romero, A. J., J. Electroanal. Chem. 2019, 850. https://doi.org/10.1016/j.jelechem.2019.113380.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Síntesis de catalizadores de base carbono (Co-N-C) para la degradación electroquímica de contaminantes

Daniel Voces a Javier Recioa, Pilar Herrastia

a Dpto. Química-Física aplicada, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, Calle Francisco Tomás y Valiente, 7, Madrid, España [email protected]

La cantidad de aguas residuales generadas y su carga total de contaminación están aumentando a nivel mundial. Por esta razón, la recuperación de estas aguas contaminadas se considera actualmente un recurso hídrico alternativo. Los procesos electroquímicos de oxidación avanzada basados en la reacción Fenton, son las tecnologías más efectivas para lograr la mineralización total de los contaminantes orgánicos en el agua. En el proceso electro-Fenton, el H2O2 se genera in situ mediante la reacción de reducción de oxígeno (ORR) vía 2 electrones. El presente trabajo se centra en la síntesis de catalizadores de base carbono de tipo Co-N-C para la electrogeneración de H2O2. Los catalizadores se sintetizaron mediante la mezcla de quitosano como fuente de C-N y distintas proporciones de sales de Co y su posterior pirólisis a 800ºC en atmósfera inerte. Los catalizadores se caracterizaron estructural y morfológicamente empleando microscopía de transmisión (TEM), difracción de rayos-X (XRD) y espectroscopía fotoelectrónica de rayos-X (XPS). La actividad catalítica y la selectividad de la reacción de ORR para la generación de H2O2 se llevo a cabo mediante voltametría cíclica (CV) y polarización lineal con electrodo de disco rotatorio a pH 3,5. La morfología muestra la nanoestructuración de los catalizadores tras el proceso de pirólisis con presencia de nanopartículas (NP). El análisis XPS reveló la presencia de sitios de tipo Co- Nx insertados en la red grafítica del material de base carbono y NP metálicas de tipo CoO y Co metálico como se confirmó mediante DRX. La CV mostró varios procesos faradaicos correspondientes a los sitios activos CoNx y a las NP de base Co. La actividad catalítica se evaluó mediante el potencial de onset (inicio de reacción), siendo el mejor catalizador en el que se utilizó una concentración inicial de 25% en peso de sal metálica de Co, con un sobrepotencial de 0.012V y una muy buena selectividad vía 2 electrones para la formación de H2O2. El potencial onset de la reacción aparece cerca del potencial redox de los sitios activos CoNx, lo que indica un mecanismo de esfera interna vía adsorción de O2 sobre los sitios CoNx. Las pendientes de Tafel tienen un valor de 120 mV, lo que indica que la primera transferencia electrónica es la etapa limitante. En base a estos resultados, se propone un mecanismo de reacción concertado entre la adsorción de O2 y la transferencia electrónica.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Metal-Organic Frameworks for Advanced Electro-Fenton Treatment of Wastewater at Near-Neutral pH: Preparation of Heterogeneous Catalysts and Enhancement of H2O2 Production

Lele Zhao Ignacio Sirés Sadornil

Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain Presenting author’s email: [email protected]

Metal-organic frameworks (MOFs) are highly ordered and porous crystalline structures synthesized from metal ion/clusters and multidentate organic ligands. Their appeal originates from the large porosity and chemical tunability, which adds to their particular catalytic nature as recently verified in MOF-catalyzed advanced oxidation processes (AOPs) [1]. However, despite the continuous development of MOFs and their application to the treatment of organic pollutants in model aqueous matrices, their structural instability and other shortcomings have been revealed, which limits their further scale-up. Some researchers have modified the synthesis routes, aiming at deriving more stable materials, some of them also showing magnetic and/or photoactive properties that can be very valuable in practice. On the other hand, MOFs can also be considered as suitable precursors of porous carbons doped with heteroatoms and/or decorated with nanoparticles, which can serve to tune the electroactivity of carbonaceous cathodes to produce H2O2 on site, as required in electro-Fenton (EF) and related processes.

The application of MOFs in electrochemical advanced oxidation processes (EAOPs) is very incipient, especially in UVA and solar photoelectro-Fenton. There are only some few works on this topic, being the host group at the University of Barcelona the first one opening this research line in 2020. Now, new heterogeneous catalysts and cathodes are needed to operate these electrochemical processes in actual wastewater at neutral or alkaline pH, since this kind of materials have been rarely compared in actual water matrices at different scales.

The synthesis (following solvothermal routes), characterization and applicability of different types of MOFs will be investigated in detail: (1) Magnetic and photoactive Fe-based MOFs will be applied as suspended catalysts in EF process and related processes; (2) carbons derived from (non-Fe)-MOFs will be used to manufacture gas-diffusion electrodes (GDEs) with enhanced H2O2 production (evaluated by means of RDE and RRDE, as well as via bulk electrolysis). We will try to identify a correlation between characteristics (morphological, structural, magnetic/photochemical) and performance of these materials, eventually coupling the new heterogeneous catalysts and GDEs in a single system. References [1] V.K. Sharma, M. Feng, J. Hazard. Mater. 372 (2019) 3–16.

Acknowledgments Financial support from PID2019-109291RB-I00 (AEI, Spain), as well as the PhD scholarship from State Scholarship Fund (CSC, China), are acknowledged.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Wednesday July 07th, 2021

8h00 - 8h15 Opening Ceremony 8h15 - 9h00 Plenary Lecture : Clément Sanchez (Room 24) (chair:Marc Fontecave)

9h00 - 10h00 Awarded Speakers (Room 24) (chair:Aranzazu Heras)

Angela Molina Albert Serra Aida Martin

10h00 - 10h30 Coffee break 10h30 - 11h10 Awarded Speakers (Room 24) (chair:Ignacio Sires) Paula Sebastian Maria Arnaiz

11h10 - 12h10 Session 1

Room 24 (chair:Marc Fontecave) Room 34ª (chair:J.L. Olloqui) C. Leger E. Gonzalez-Romero L. Merakeb R. Miranda-Castro R. Aran-Ais S. Guerrero O. Gutierrez A. de la Escosura

12h10 - 13h30 General Assembly GE-RSEQ 13h30-15h Lunch

15h - 16h15 Session 2 Room 24 (chair:Gonzalo Guirado) Room 34A (chair:Alvaro Colina) G. Diaz-Sainz V. Serafin Gonzalez

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

F. Martinez N. Felipe B. Avila Bolivar A. Valverde T. Andreu H. Cunha-Silva J. Hernandez-Ferrer R. Jimenez-Perez

16h15-16h45 Coffee break

16h45 - 17h45 Session 3 Room 34A (chair: Alberto Room 24 (chair:Sergi Garcia) Hernandez) G. Rosello-Marquez M. Revenga R. Oriol E. Valero V. Poza Nogueiras J.M. Diaz-Cruz M. Carvela Soler F. Prieto

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Integrative materials chemistry: a multidisciplinary domain

Clément Sanchez

Laboratoire de Chimie de la Matière Condensée de Paris, CNRS-Université Pierre et Marie Curie. Collège de France, Paris https://www.college-de-france.fr/site/clement-sanchez/Biographie.htm Presenting author’s email: [email protected]

Hybrid inorganic-organic materials can be broadly defined as synthetic materials with organic and inorganic components which are intimately mixed. They can be either homogeneous systems derived from monomers and miscible organic and inorganic components, or heterogeneous and phase-separated systems where at least one of the components’ domains has a dimension ranging from a few Å to several nanometers. Hybrid phases can also be used to nanostructure or texture new inorganic nanomaterials (porous or non porous). The versatile synthetic conditions provided by bottom up strategies such as reactive molecular precursors or clusters, tunable processing temperatures and solvents and the adjustable rheology of the colloidal state allow for the mixing of the organic and inorganic components at the nanometer scale in virtually any ratio. These features, and the advancement of organometallic chemistry and polymer and sol-gel processing, make possible a high degree of control over both composition and structure (including nanostructure) of these materials, which present tunable structure-property relationships. This, in turn, makes it possible to tailor and fine-tune properties (mechanical, optical, electronic, thermal, chemical…) in very broad ranges, and to design specific systems for applications. Hybrid materials can be processed as gels, monoliths, thin films, fibers, particles or powders or can be intermediates to design materials having complex shapes or hierarchical structures. The seemingly unlimited variety, unique structure- property control, and the compositional and shaping flexibility give these materials a high potential in sensing, membranes, catalysis, biocatalysis, photocatalysis, nanomedicine, the tailoring of smart functional surfaces etc…. This lecture will describe some recent advances on this integrative materials chemistry that allows via a chemistry-process coupling to tailor made nanostructured and hierarchically structured functional inorganic and hybrid materials. Some of their properties will also be discussed.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Theoretical treatments devoted to unravel reaction mechanisms at solid-liquid and liquid-liquid interfaces and microinterfaces

Angela Molina, Francisco Martínez-Ortiz, Carmen Serna, Manuela López-Tenés, Joaquín González, and Eduardo Laborda

Departamento de Química Física, Facultad de Química, Universidad de Murcia (Spain) [email protected]

Heterogeneous charge transfer processes (ion and electron) are very frequently complicated with chemical reactions the electroactive species take part of. For almost forty years, our research team has been devoted itself fundamentally to the study of these processes, with special attention to electrocatalytic processes for their implications in energy generation and storage, electroanalysis and biological electron transfer processes. These studies have been carried out through different electrochemical techniques, either already existing or newly designed by ourselves. In all the cases that we have been able to solve, we have obtained analytical expressions, almost always rigorous and easily programable. Through a thoughtful a priory analysis of this equations, it has been possible to identify the chief parameters, as well as to obtain very simple expressions for limit cases of interest.

Recently, an extensive theory for complex electrocatalytic multi-electronic mechanisms, the combination of electrochemical and spectroscopic techniques, as well as for nanoparticle impact experiments, has been carried out, pointing out the advantages for the identification of chemical species and reaction pathways.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Electrosynthesis of biomimetic photocatalysts for water decontamination Albert Serrà a, b a Thin films and nanostructures electrodeposition, Department of Materials Science and Physical Chemistry, Universitat de Barcelona, Martí i Franquès, 1, E-08028 Barcelona, Catalonia, Spain b Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, E-08028 Barcelona, Catalonia, Spain Presenting author’s email: [email protected] Identifying sources of green energy and decontaminating water are two of the current generation’s most vital social and global challenges. In recent decades, important advances have been made in developing new materials, systems, and technologies to enhance the generation of green energy or the elimination of emerging pollutants. However, such development has often focused on linear processes that start from raw materials and end with the production of new waste. Against that trend, electrochemical deposition is a basic but powerful tool for fabricating efficient biomimetic photocatalysts for use in decontaminating water. In this presentation, I will describe a holistic approach based on electrochemical deposition, including electrodeposition and electroless deposition, for fabricating more efficient bioinspired photocatalysts that can significantly improve the efficiency of light delivery. To support the approach, four major activities have been undertaken: o The electrodeposition of biomimetic photocatalysts. Different strategies were investigated to promote the deposition of biomimetic structures that simultaneously improve the adsorption of pollutants and the light-trapping capacity 1. o The investigation and integration of biotemplates with electroless deposition. The use of different biotemplates (e.g., microalgae and pollen) were explored as supports for the electrosynthesis of hybrid photocatalysts. The electroless deposition of magnetic materials was also examined to provide them with magnetic functionality and to aid the electroless deposition of semiconductors able to produce an onion-like core@shell photocatalyst. The goal is to take advantage of the shape and architecture of some microorganisms in order to improve light absorption 2. o The investigation of the photocatalytic mineralization of emerging pollutants. The mineralization of different emerging pollutants, including antibiotics and biotoxins, was studied via sunlight photocatalysis, as were the stability and reusability of photocatalysts 2. o The realization of recyclability to ensure circular chemistry for water decontamination. The biohybrid nature of biotemplates allows (i) maximizing the capacity to absorb sunlight and consequently improving the photodegradation of emerging pollutants via photocatalysis; and (ii) recycling photocatalysts at the end of their useful lives as raw materials for the production of biofuel. Such steps can facilitate the design of a holistic, green, scalable, economical, waste-free circular process that simultaneously integrates the creation of green energy sources and the purification of water 2. References (1) Serrà, A.; Zhang, Y.; Sepúlveda, B.; Gómez, E.; Nogués, J.; Michler, J.; Philippe, L. Highly Active ZnO-Based Biomimetic Fern-like Microleaves for Photocatalytic Water Decontamination Using Sunlight. Appl. Catal. B Environ. 2019, 248 (January), 129–146. (2) Serrà, A.; Artal, R.; García-Amorós, J.; Sepúlveda, B.; Gómez, E.; Nogués, J.; Philippe, L. Hybrid Ni@ZnO@ZnS-Microalgae for Circular Economy: A Smart Route to the Efficient Integration of Solar Photocatalytic Water Decontamination and Bioethanol Production. Adv. Sci. 2020, 7 (3), 1–9.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Programmed lysis for dynamic bacterial resistors

Aida Martin1*, Omar Din1*, and Jeff Hasty1,2,3

1BioCircuits Institute, University of California, San Diego, La Jolla, California 92093, USA. 2Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA 3Molecular Biology Section, Division of Biological Science, University of California, San Diego, La Jolla, California 92093, USA.

Electrochemical sensors are increasingly being used to investigate different aspects of cell growth, division, and morphology. While the measurement of electrochemical impedance has increasingly been investigated as a strategy to detect bacterial growth via metabolic byproducts, an intriguing possibility is the use of impedance to measure dynamic gene expression. Such an intersection between gene expression and impedance would benefit from the population control tools of synthetic biology. Here, we use programmed lysis to control the biochemical impedance of a bacterial culture over time1. The bacterial population acts as an oscillatory resistor when we use a synchronized lysis circuit, or as a manually controlled resistor when we use an induced lysis circuit. We demonstrate the ability of these circuits to dynamically change the impedance of a culture by modulating the bacterial population in macro-chemostats. Guided by these findings, we probe the applicability of these bacterial resistors as a biosensing platform by constructing a lysis circuit activated in the presence of arsenic. We develop a microfluidic device with integrated electrodes to test this construct and we find that we can electrochemically detect the change in culture impedance in response to arsenic at this scale. Interfacing gene expression with population control for impedance measurements may represent a label-free and simplified monitoring or tracking system over traditional imaging methods for sensing applications.

(1) M. O. Din*, A. Martin*, I. Razinkov, N. Csicsery, J. Hasty. Interfacing gene circuits with microelectronics through engineered population dynamics. Science Advances, 2020, 6, 21, eaaz8344 * Equally contributed to this work

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Surface influence on the first stages of the metal electrodeposition in ionic liquids

Paula Sebastián Pascuala

a Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark paula.pascual＠chem.ku.dk

The doctoral thesis aims to assess the applicability of different classes of ionic liquids (ILs) for the electrodeposition of metallic nanostructures onto different substrates. In particular, room temperature ionic liquids (RTILs) and deep eutectic solvents (DES), were considered as solvents for metal electrodeposition. As RTIL, the [Emmim][Tf2N] (1-ethyl-2,3- dimethylimidazolium bis(trifluoromethylsulfonyl)imide) was selected, whereas the ChCl:urea (choline chloride plus urea) was the employed DES to conduct the electrodeposition of different metals. The principal goal of this thesis was investigating, from a fundamental point of view, the way how these types of solvents affect the first stages of the metal deposition mechanism and its influence on the morphology and distribution of deposited nanostructures. Electrodeposition of Ag, Cu and Ni were specifically considered. Single crystal electrodes were necessarily included in this analysis as parameter to elucidate the surface influence in the process. Before investigating the metal electrodeposition mechanism, analysis of the properties and electrochemistry of different metallic single crystal electrodes in contact with the ILs was performed, aiming to obtain a rational description of these electrified interfaces. The study of the structure of the Metal | ionic liquid interface was performed using the laser induced temperature jump technique, for estimation of the potential of zero charge. The obtained results in ionic liquid media were compared with those obtained for the classical Metal | aqueous solution interface.

A 15 10 Au(111)|EmmimTf2N A Au(111)|ChCl:urea B 10 -2 5 5 A cm

 0

j / -5 -5 -10 -10 -15 -1.0 -0.5 0.0 0.5 1.0 1.5 -1.0 -0.5 0.0 0.5 E / V vs Ag E / V vs Ag

Figure 1: Blank cyclic voltammetry of two Au(111)|IL interfaces at 50 mVs-1.

(1) Sebastián-Pascual, P.; Surface influence on the first stages of the metal electrodeposition in ionic liquids. Thesis dissertation, 2018, Alicante. Supervisors: Juan Miguel Feliu; Elvira Gómez-Valentin.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Development of Lithium and Sodium ion capacitors with high energy-to- power ratios

María Arnaiz

Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, 01510 Vitoria-Gasteiz, Spain. [email protected]

Metal ion capacitor technology (MIC, being M = L for Li and N for Na) was first developed in the early 2000’s as a novel approach based on the internal hybridization of lithium-ion batteries (LIBs) and electrical double layer capacitors (EDLCs). These systems hold promise to merge the best features of each technology, achieving high energy densities, thanks to the battery-type electrode, at high power densities, owing to the capacitor-type electrode, while maintaining long cycle life. Since the first commercial lithium-ion capacitor reached the market in 2008, research on this field has notoriously increased. However, most of the developed systems gain energy at the expenses of power and/or cycle life. Hence, the aim is to develop more energetic, more powerful and more stable lithium and sodium ion capacitors (LICs and NICs). In this scenario, the activated carbon (AC) has been the material of choice for the capacitor-type positive electrode owing to its fast response, stability and low-cost, while for the battery-type negative electrode three different faradaic materials with their own particular set of assets have been investigated. Hard carbon (HC), SnO2 embedded in a reduce graphene oxide matrix (SnO2-rGO) and TiSb2 intermetallic compound have been the selected materials. LICs and NICs have been developed with HC and TiSb2 while the use of SnO2-rGO has been limited to Li-ion technology owing to the poor performance shown in Na-ion. The selection of these specific battery-type materials has been driven by their low reduction potential and high specific capacity response. Being the energy density of a MIC described by the specific capacitance and the cell voltage of the device, the use of the selected materials allows targeting for high energy density outputs. In order to be able to also give response at high rates, i.e. at low discharge times, ensuring also high power density outputs, the preparation of each material as well as the electrodes have been optimized. To this end, reduction on particle size for HC and TiSb2, and carbon/graphene coating techniques for SnO2-rGO and TiSb2 materials have been followed. Finally, in order to neutralize the large volume changes that alloying materials (i.e. Sn and Sb) suffer during cycling; different strategies have been followed in order to achieve high durability devices. In the case of SnO2-rGO, the graphene matrix itself plays a role buffering volume expansion/contractions. In the case of TiSb2, a titanium matrix only capable of mitigating the Li-based alloy volume changes (Li3Sb, 135%) was used while for the larger Na-based alloy volume expansions (Na3Sb, 293%) an additional study in the TiSb2 electrode fabrication process has been carried out studying the effect of different binders. Overall, with the studied different negative electrode materials, more energetic, more powerful and more stable LICs and NICs have been possible to develop.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Understanding and designing bidirectional and reversible molecular catalysts of redox reactions, under conditions of direct or mediated electron transfer

Vincent Fourmond (a), Nicolas Plumeré (b), Christophe Léger (a) a CNRS, Aix Marseille Université, Marseille, France b Technical University Munich, Straubing, Germany [email protected] https://bip.cnrs.fr/groups/bip06/

The performance of a catalyst (be it a synthetic molecular catalyst, an enzyme or even a biological motor) is most often considered in terms of rate. A distinct figure of merit of any catalyst is related to how much driving force is needed to make it work; we and others have called “reversible” the bidirectional molecular catalysts that function at a high rate in response to even a small departure from equilibrium (1). Reversible catalysts are desirable, because they do not dissipate the chemical or electrical energy that is input to drive the transformation. In particular, understanding what makes some catalyst function reversibly is crucial in the solar fuels field, where efficient and cheap catalysts are needed to store in the form of chemicals (such as H2) the energy collected from intermittent sources. Reversible catalysis is common in Nature (e.g. the enzymes hydrogenases reversibly produce and oxidize H2), but it has been difficult to characterize experimentally and to engineer in molecular catalysts. We have recently proposed the first kinetic analytical models that describe bidirectional two- electron catalysis under conditions of direct (2) and mediated (3) electron transfer. We have + examined various experimental situations where bidirectional and reversible H /H2 is obtained, with biomimetic catalysts or enzymes directly wired to electrodes (2) or embedded in redox polymers (3). From a fundamental point of view, this approach helps understand the molecular and kinetic determinants of catalytic (ir)reversibility (2b). To demonstrate the importance of these findings interms of applications, we could make a “reversible” hydrogenase electrode by embedding the enzyme in a low-potential redox polymer. We used it as the anode of a H2/O2 biofuel cell whose OCV reached 1.16V, near the thermodynamic limit. High current densities and Faraday efficiencies for either H2 oxidation and production were obtained at a small overpotential (3).

References (1) Fourmond, V., Plumeré, N., Léger, C. “Reversible catalysis”. Nature Reviews Chemistry 2021 (in press) doi:10.1038/s41570-021-00268-3 (2) (a) Fourmond, V, et al, “Steady-state catalytic wave-shapes for 2-electron reversible electrocatalysts and enzymes” J. Am. Chem. Soc. 2013 125 3926. (b) Fourmond, V., Wiedner, E. S., Shaw, W. J., Léger, C. “Understanding and Design of Bidirectional and Reversible Catalysts of Multielectron, Multistep Reactions” J. Am. Chem. Soc. 2019 141, 11269–11285. (3) Hardt, S., Stapf, S., Filmon, D. T., Birrell, J. A., Rüdiger, O., Fourmond, V., Léger, C. & Plumeré, N., “Reversible H2 Oxidation and Evolution by Hydrogenase Embedded in a Redox Polymer Film” Nature Catalysis 2021 4, 251–258.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

How electricity understands chemistry: proof of concept for portable device fabrication and its applications

a a a,b Elisa González-Romero, Javier M. González-Costas, Ana M. Prado-Comesaña, María b b b Arellano, Marta Pazos, and M. Ángeles Sanromán a Electroanalysis and Biosensors,Department of Analytical and Food Chemistry, University of Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain b CINTECX, Universidade de Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain [email protected]

We present a proof-of-concept demonstration of a portable device screen-printed carbon-based sensor useful for a wide range of applications as drug control in pharmaceuticals, drug detection in environmental (tap water) or drug monitoring during degradation process by Advance Oxidation Processes (AOPs) in contamined tap water with specific medicines. The sensor represents the first example of a portable drug-meter device combining the sensitivity of Differential Pulse Voltammetric technique (DPV) and the selectivity of Screen-Printed Carbon Electrode (SPCE) technology for the detection and quantification of micro contaminants in highly complex samples. In-situ electrochemical studies reveal the drug-meter’s response toward low drug level concentration with no interferences from common coexisting electroactive species. Correlation of the drug sensor response with that of conventional potentiostat/galvanostat equipment underscores the promise of the portable device sensor to detect drug levels in cheap, fast and any place fashion with a very low volume of sample used, without any previous sample treatment, being operative in suspensions and opaque media. In addition, it can be extended toward detection and degradation monitoring of the pollutant present in complex samples at very low concentration (Limit of Detection, LOD, calculated as the concentration corresponding to three times the standard deviation of the intercept, 835 ngL-1) with very good precision (expressed as Relative Standard Deviation, RSD 3.7%) and high accuracy (recoveries around 98% using standard addition technique). Control on-pharmaceuticals, on-environmental and on-AOPs process evolution experiments demonstrate the importance of the direct operation to evaluate the matrix effect and validate the sensor specificity. This preliminary investigation indicates that the screen-printed carbon-based sensor platform holds considerable promise for efficient control and management in different fields. Finally, aspects related to the analytical performance of the developed device until its fabrication by Metrohm-Dropsens with the corresponding transfer of knowledge to society together with prospects for future improvements and applications are discussed.

Acknowledgements This work has been supported by the Spanish Ministry of Science, Innovation and Universities and European Regional Development Fund through projects CTM2017-87326-R, CTQ2017-90659- REDT and RED2018-102412-T, Xunta de Galicia and European Regional Development Fund Projects ED431C 2017/47 and ReGaLIs ED431 2017/11. María Arellano is grateful to Xunta de Galicia and European Social Fund (ESF) for her mobility and PhD grants.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Molybdenum drives electrochemical dinitrogen splitting

Lydia Merakeb,a Soukaina Bennaamane,b Nicolas Mézaillesb and Marc Roberta,c

a Laboratoire d’Electrochimie Moléculaire – UMR 7591, Paris, France b Laboratoire Hétérochimie Fondamentale et Appliquée – UMR 5069, Toulouse, France c Institut Universitaire de France, Paris, France

[email protected]

Although naturally abundant, nitrogen is mostly present in the vast atmospheric reservoir of chemically inert N2. It is consequently a limiting nutrient in agriculture. While nature has found its way into activating N2 via nitrogenase enzymes, modern agriculture (and industry) are essentially sustained by the Haber – Bosch process that converts N2 (originating from fossil sources) and H2 into ammonia over an iron catalyst and under harsh operating conditions (350 – 550 °C, 150 – 350 atm.).1 Greener and more sustainable processes are needed.

Over the last years, chemists have been designing molecular catalysts able to react with N2, cleave it and functionalize it.2 These synthetic systems include molybdenum, iron and rhenium complexes. And while homogeneous catalysis of N2 fixation is gaining momentum, development of electrochemical systems based on well-defined complexes remains sluggish and only a few examples have emerged.

In the work presented here, we explored the electrochemical splitting of dinitrogen with a molybdenum molecular complex leading to the corresponding Mo-nitride.3 An analogous molecular complex has previously been demonstrated to undergo such a process in homogeneous conditions and in the presence of a chemical reductant.4,5

(1) Schlögl, R., Angew. Chem. Int. Ed., 2003, 42 (18), 2004–2008. (2) Chalkley, M. J.; Drover, M. W.; Peters, J. C., Chem. Rev. 2020, 120 (12), 5582–5636. (3) Merakeb, L.; Bennaamane, S.; Mézailles, N.; Robert, M., 2021., submitted. (4) Liao, Q.; Saffon-Merceron, N.; Mézailles, N., ACS Catal. 2015, 5 (11), 6902–6906. (5) Liao, Q.; Cavaillé, A.; Saffon-Merceron, N.; Mézailles, N., Angew. Chem., 2016, 128 (37), 11378–11382.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Electrochemical biosensing platforms for monitoring long non-coding RNAs: towards a more reliable early detection of prostate cancer

Rebeca Miranda-Castro,a,b Raquel Sánchez-Salcedo,a,b Clara Abardía-Serrano,a,b Noemí de- los-Santos-Álvarez,a,b María Jesús Lobo-Castañón a,b

aDpto. Química Física y Analítica, Facultad de Química, Universidad de Oviedo, Av. Julián Clavería 8, 33006 Oviedo, Spain bInstituto de Investigación Sanitaria del Principado de Asturias, Av. de Roma, 33011 Oviedo, Spain [email protected]

The early detection of cancer is decisive to improve the patient’s chances of cure and survival. To tackle this great challenge, the current trend is the search for molecules released by tumor cells to body fluids that warn of the disease in the earliest stages, the so-called liquid biopsy that, unlike traditional tissue biopsy, is characterized by its minimally invasive nature and few risks associated. Among cancer-related biomarkers that circulate in the accessible biological fluids, long non-coding RNAs (lncRNAs) have gained momentum in the recent years. They are > 200 nucleotide long transcripts with no protein-coding capacity, thus defying the central dogma of molecular biology and, interestingly, the aberrant expression of some lncRNAs has proven to be a reliable predictor of cancer. Electrochemical sensing strategies based on the hybridization reaction for detecting circulating nucleic acids of clinical significance have appeared as a selective, fast, decentralized, and low-cost alternative to in-vitro diagnostics, although their application to cancer-related lncRNAs monitoring is scarce [1].

In this work, we describe the development of electrochemical sandwich hybridization assays for the detection of prostate cancer antigen-3 or PCA3, a urinary lncRNA approved by FDA for prostate cancer diagnosis [2]. With the goal of detecting clinically relevant PCA3 levels, we evaluate comparatively the use of the redox enzyme HRP as a reporter incorporated via high- affinity fluorescein-Fab antifluorescein interaction, and the implementation of an isothermal DNA amplification strategy such as rolling circle amplification (RCA). Likewise, two different portable electrochemical platforms are assessed, disposable screen-printing electrochemical cells as well as the most successful commercial biosensor used daily by millions of diabetic people worldwide: the personal glucose meter [3].

References (1) Miranda-Castro, R., de-los-Santos-Álvarez, N., Lobo-Castañón, M.J. Anal. Bional. Chem. 2019, 411, 4265-4275. (2) Sartori, D.A., Chan, DW-Y. Curr. Opin. Oncol. 2014, 26, 259-264. (3) Xiang Y., Lu Y. Nature Chemistry 2011, 3, 697-703.

Acknowledgements The work has been financially supported by Spanish Government (project RTI-2018-095756- B-I00) and Principado de Asturias government (Project IDI/2018/000217, co-financed by FEDER funds).

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Facet-Dependent Electrochemistry: Model Surfaces and Tailored Nanocatalysts for CO2 Electroreduction

Rosa M. Arán-Ais,a,b Fabian Scholten,b Sebastian Kunze,b Rubén Rizo,a,b and Beatriz Roldan Cuenyab a Instituto de Electroquímica, Universidad de Alicante, Spain b Department of Interface Science, Fritz-Haber-Institut der Max-Planck Gesellschafts, Berlin, Germany. [email protected]

The electrochemical conversion of CO2 to chemicals and fuels powered by the electricity derived from renewable energy sources is a promising strategy towards sustainable energy. Highly active and selective electrocatalysts for multicarbon products are urgently needed to 1 improve the energy efficiency of the CO2 reduction reaction (CO2RR) . Therefore, a multi- pathway strategy is applied considering the design of advanced catalysts with tailored activity/selectivity-determining properties but also advanced electrochemical routines leading to an in situ transformation towards highly selective catalysts and/or to optimized reaction conditions for C2+ formation.

In this work, we present novel strategies to gain simultaneous control over the surface structure and composition of Cu single crystal electrodes achieved by using a pulsed potential technique. Quasi in situ X-ray photoelectron spectroscopy (XPS) helped us to identify the oxidation state of surface species generated by the anodic pulses, while the surface structure of the electrodes was monitored by cyclic voltammetry (CV). Our results point out that the concurrency of (100) 2 sites and Cu(I) surface species are the best combination towards the C2+ products pathway .

Following these findings, shape-selected Cu2O nanocubes exposing (100) facets were investigated applying different methodologies. Wet-chemical synthesized Cu2O nanocubes showed high performance for the CO2RR towards ethylene. However, by using liquid cell transmission electron microscopy (LC-TEM) 3 we observed that the re-structuring of similar electrodeposited structures can be the main factor leading to the deactivation of these catalysts.

References

(1) Arán-Ais, R. M.; Gao, D.; Roldan Cuenya, B. Structure- and Electrolyte-Sensitivity in CO2 Electroreduction. Acc. Chem. Res. 2018, 51 (11), 2906. (2) Arán-Ais, R. M.; Scholten, F.; Kunze, S.; Rizo, R.; Roldan Cuenya, B. The Role of in Situ Generated Morphological Motifs and Cu(I) Species in C2+ Product Selectivity during CO2 Pulsed Electroreduction. Nat. Energy 2020, 5 (4), 317. (3) Arán-Ais, R. M.; Rizo, R.; Grosse, P.; Algara-Siller, G.; Dembélé, K.; Plodinec, M.; Lunkenbein, T.; Chee, S. W.; Cuenya, B. R. Imaging Electrochemically Synthesized Cu2O Cubes and Their Morphological Evolution under Conditions Relevant to CO2 Electroreduction. Nat. Commun. 2020, 11 (1), 3489.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Simultaneous Determination of MMP-3 and CXCL7 in autoimmune diseases by a Dual Electrochemical Magneto Immunosensor

Sara Guerrero, Esther Sánchez-Tirado, Lourdes Agüí, Araceli González-Cortés, Paloma Yáñez- Sedeño and José Manuel Pingarrón Analytical Chemistry Dept., Faculty of Chemistry, University Complutense of Madrid, Spain [email protected]

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that primarily affects the lining of the synovial joints and is associated with progressive disability, premature death, and socioeconomic burdens1. The development of sensitive and accurate methods for the detection of RA biomarkers is an essential tool for achieving an effective early and reliable clinical diagnosis2. MMP-3 belongs to a family of proteins which are known to be important proteases responsible for extracellular matrix protein degradation. It is considered an important pathological mediator of RA. Measurement of active MMP-3 in clinical samples could provide information about progression of rheumatoid diseases, and potentially response to treatment3. On the other hand, CXCL7 is part of the group of chemokines and is a potent chemoattractant and activator of neutrophils. This chemokine is highly expressed in serum, synovial fluid and synovial tissue of patients developing RA during the first 12 weeks. However, it is expressed at lower levels in RA with longer duration, this variation being useful to reflect local pathological changes4. This work describes the development of the first electrochemical immunosensor for the simultaneous determination of MMP-3 and CXCL7. As can be seen (Fig. 1), a dual sandwich-type immunosensor was prepared based on the use of magnetic micro beads modified with carboxylic groups. Both affinity reactions were monitored by using streptavidin labeled with horseradish peroxidase (HRP-Strept), in combination with H2O2 and hydroquinone. All involved experimental variables were optimized and a good reproducibility was reached. Likewise, analytically useful signals have been obtained by amperometry, as well as a calibration plot in a suitable concentration range for its application to clinical samples.

Figure 1. Dual immunosensor scheme for CxCL7 and MMP-3 determination.

References: (1) Guo, Q.; Wang, Y. et al. Bone Research 2018, 6, 15. (2) Aletaha, D.; Smolen, J.S. JAMA 2018, 320, 1360. (3) Sun, S.; Bay-Jensen, A.C. et al. BMC Musculoskelet Disord 2014, 15, 93. (4) Guerrero, S.; Cadano, D. et al. Journal of Electroanalytical Chemistry 2019, 837, 246.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Nanochannels for electrochemical biosensing: application to bacterial virulence evaluation

Kristina Ivanova,a Tzanko Tzanov,a and Alfredo de la Escosura-Muñizb

a Grup de Biotecnologia Molecular i Industrial, Department of Chemical Engineering, Universitat Politècnica de Catalunya, Terrassa, Spain b NanoBioAnalysis Group- Department of Physical and Analytical Chemistry, University of Oviedo, Julián Clavería 8, 33006, Oviedo, Spain

[email protected]

Nanochannels are emerging platforms with outstanding potential for a variety of electrical biosensing applications (1). In this context, we propose here a novel methodology for electrical monitoring using nanoporous alumina membranes of virulence factors secreted by bacterial pathogens (2). Bacterial hyaluronidase (HYAL), which is produced by a number of invasive Gram-positive bacteria (3), is selected as a model compound to prove the concept. Our electrochemical setup takes advantage of the flat surface of indium tin oxide/poly(ethylene terephthalate) (ITO/PET) electrodes for their assembly with the nanoporous membrane. The proposed analytical method, based on the electrical monitoring of the steric/electrostatic nanochannels blocked upon formation of an antibody−HYAL immunocomplex, reached detection limits as low as 64 UI/mL (17.3 U/mg) HYAL (3). The inert surface of the ITO/PET electrodes together with the anti-biofilm properties of the 20 nm pore-sized alumina membranes allows for culturing the bacteria, capturing the secreted enzymes inside the nanochannels, and removing the cells before the electrochemical measurement. Secreted HYAL at levels of 1000 UI/mL (270 U/mg) are estimated in Gram-positive Staphylococcus aureus cultures, whereas low levels are detected for Gram-negative Pseudomonas aeruginosa (used as a negative control). Finally, HYAL secretion inhibition by RNAIII inhibiting peptide (YSPWTNF-NH2) is also monitored, opening the way for further applications of the developed monitoring system for evaluation of the antivirulence potential of different compounds. This label-free method is rapid and cheap, avoiding the use of the time-consuming sandwich assays. We envisage future applications for monitoring of bacterial virulence/invasion as well as for testing of novel antimicrobial/antivirulence agents.

References: (1) (a) De la Escosura-Muñiz, A.; Merkoçi, A. ACS Nano 2012, 6(9), 7556-7583. (b) De la Escosura-Muñiz, A.; Merkoçi, A. TRAC 2016, 79, 134-150. (c) De la Escosura- Muñiz et al. Biosens. Bioelectron. 2018, 107, 62-68. (d) De la Escosura-Muñiz, A.; Merkoçi, A. Small 2011, 7, 675-682. (e) De la Escosura-Muñiz, A.; Merkoçi, A. Electrochem. Commun. 2010, 12, 859-863. (2) De la Escosura-Muñiz et al. ACS Appl. Mater. Interfaces 2019, 11, 13140-13146. (3) Hynes, W.L.; Walton, S-L. FEMS Microbiology Letters 2000, 183, 201-207.

Acknowledgements: We acknowledge funding by the ERA-NET EuroNanoMed II PCIN-2016-134 project, the FC-GRUPIN-ID/2018/000166 project from the Asturias Regional Government and the CTQ2017-86994-R project from MINECO (Spain). A. de la Escosura- Muñiz acknowledges MICINN (Spain) for the “Ramón y Cajal” Research Fellow (RyC-2016-20299).

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

A comparative assessment of different nature electrocatalysts and electrode configuration for the continuous electroreduction of CO2 to formate Guillermo Díaz Sainz,a Manuel Álvarez Guerra,a and Angel Irabiena aChemical and Biomolecular Engineering Department, University of Cantabria, Avda de los Castros s/n, Santander, 39005, Spain [email protected] Climate change mitigation has become one of the most important challenges in the 21st century. For this reason, the carbon dioxide (CO2) capture, storage, and utilization approaches (CCSU), and, particularly, the CO2 electroreduction to value-added chemicals, have gained increasing attention in recent years. In particular, both formic acid and formate are products that could be obtained by this electrochemical process of great interest, due to its use as raw materials in several industries, such as textile, rubber manufacture, medicine or animal feed, as well as its promising use as a fuel in low-temperature fuel cells and as a renewable hydrogen carrier molecule (1). In this context, the research group “Development of Chemical processes and Pollution Control” (DePRO) of the Chemical and Biomolecular Engineering Department at the University of Cantabria has made great efforts in this research topic for over a decade, working with electrocatalysts of different nature and electrode configurations. Therefore, this communication aims at presenting a rigorous comparative assessment of different experimental data obtained in our installations operating with Sn and Bi-based materials, both supported on carbon, under Gas Diffusion Electrodes (GDEs) and Catalyst Coated Membrane Electrodes (CCMEs) configurations in a continuous mode with a single pass of the inputs through the reactor for the electrocatalytic reduction of CO2 to formate. In general, it can be highlighted that the use of Bi enhances the process performance with respect to the employ of Sn under the same conditions in GDE and CCME cathode configurations. In contrast, although the results of the process are more favorable energetically with a CCME configuration, the GDE configuration allows working at higher current densities, up to 300 mAꞏcm-2, in comparison with CCMEs. In addition, this assessment also highlights that in CCME configuration, the employ of Bi-based-electrodes enhanced the behavior of the process, increasing the formate concentration by 35% and the Faradaic efficiency by 11% (2). Finally, despite the notable advances achieved, further research is necessary to optimize all the figures of merit analyzed in this work by studying innovative electrochemical reactor configurations (3). Acknowledgements Authors fully acknowledge the financial support received from the Spanish State Research Agency (AEI) through the projects CTQ2016-76231-C2-1-R (AEI/FEDER, UE) and the project PID2019-108136RB-C31 (AEI/10.13039/501100011033).

References (1) An, X.; Li, S.; Hao, X.; Xie, Z.; Du, X.; Wang, Z.; Hao, X.; Abudula, A.; Guan, G. Renewable and Sustainable Energy Reviews 2021, 143, 110952. (2) Díaz-Sainz, G. (2021). Electrochemical CO2 utilization: development of a continuous process for obtaining formate with high efficiency (PhD Thesis), ISBN: 978-84-09-29699-6. (3) Díaz-Sainz, G.; Alvarez-Guerra, M.; Avila-Bolívar, B.; Solla-Gullon, J.; Montiel, V.; Irabien, A. Chemical Engineering Journal 2021, 405, 126965.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Faster and sensitive amperometric biosensor for detection of autoimmune disorders through serum autoantibodies determination

Verónica Serafín,a Beatriz Arévalo,a Marta Sánchez-Paniagua,b Ana Montero,c Rodrigo Barderas,c Beatriz López-Ruíz,b Susana Campuzano,a Paloma Yáñez-Sedeño,a and Jose Manuel Pingarróna

a Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, Ciudad Universitaria S/N, 28040, Madrid, Spain. b Department of Chemistry in Pharmaceutical Sciences, Faculty of Farmacy, University Complutense of Madrid, Ciudad Universitaria S/N, 28040, Madrid, Spain c UFIEC, Institute of Salud Carlos III, 28220 Majadahonda, Madrid, Spain [email protected]

Connective tissues diseases (CTD) are chronic inflammatory pathologies of autoimmune disorders which are characterized by the presence of antinuclear antibodies (ANAs) against own epitopes in the blood. ANAs are specific class of autoantibodies that have the capability of binding and destroying certain structures within the nuclear of the cells. These include antibodies against double-stranded DNAs (dsDNA), which are widely used for diagnosis and pathogenesis of CTD. Indeed, the serum or plasma concentrations of anti-dsDNA IgGs, IgMs and IgA have demonstrated to exhibit positive correlation to the severity of the disease having set a cut-off value of 25 U mL-1 to discriminate between healthy donors and autoimmune disease patients. The determination of these particular autoantibodies is carried out by traditional techniques such as Enzyme Linked Immunosorbent Assays (ELISAs), which are time-consuming, require skilled technicians and are neither affordable for all laboratories nor compatible with decentralized analysis. In this work we describe the development of a novel amperometric biosensor based on the use of neutravidin magnetic microbeads (NA-MBs) modified with a biotinylated-dsDNA, prepared in the laboratory from human plasmid, as efficient magnetic microcarriers to selectively capture the target autoantibodies present in the sera of patients. Subsequently, the attached autoantibodies are detected with a mixture of conventional HRP-labeled secondary antibodies (HRP-anti-human IgG/IgM/IgA mixture), and the biorecognition event is monitored using amperometric transduction at −0.20 V (vs Ag pseudoreference electrode) with the hydroquinone (HQ)/H2O2 system upon capturing the final modified MBs on the surface of screen-printed electrodes (1). The resulting bioplatform provides a linear calibration plot ranging from 0.98 to 200 U mL−1, a LOD of 0.3 U mL−1 for anti-dsDNA antibodies standards and potential to perform the accurate determination of the autoantibodies levels directly in 100- times diluted serum samples from patients diagnosed with rheumatoid diseases.

(1) Arévalo, B.; Serafín, V.; Sánchez-Paniagua, M.; Montero-Calle, A.; Barderas, R.; López-Ruíz, B.; Campuzano, S.; Yáñez-Sedeño, P.; Pingarrón, J.M. Biosensors & Bioelectronics 2020, 160, 112233; doi: 10.1016/j.bios.2020.112233

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Cu nanoparticles deposited on carbon supports for the electrochemical reduction of CO2 with gas diffusion electrodes

Fabiola Martínez, Carlos Jiménez, María Isabel Cerrillo, Rafael Camarillo, Isaac Asencio and Jesusa Rincón

Universidad de Castilla-La Mancha, Faculty of Environmental Sciences and Biochemistry, Department of Chemical Engineering. Avenida Carlos III, s/n, 45071 Toledo, SPAIN [email protected]

The increase of carbon dioxide emissions from anthropogenic activities in the last decades is one of the most important environmental problems in our days. CO2 capture and conversion to fuels and chemical feedstocks is one of the measures that can help to diminish the emissions of this gas. The electrochemical reduction of CO2 is a promising alternative to tackle that task. Nevertheless, the development of efficient, selective and stable electrocatalysts is still a challenge for its industrial application. In this context, the synthesis of nanostructured catalysts by supercritical fluid deposition (SFD) is being studied by our group. SFD is an environmentally friendly technology that has been successfully used to obtain electrocatalysts for different applications (1). The deposition of Cu based nanoparticles on carbon supports has been carried out in this work. The carbon supports studied are carbon nanotubes (CNT), carbon black (CB) and reduced graphene oxide (rGO). Deposition yields over 85 % in SFD have been attained independently of the carbon support used. The activity of these catalysts in the electrochemical reduction of CO2 in gas phase has been tested in a polymer electrolyte membrane (PEM) type cell. The electrocatalysts have been set in gas diffusion electrodes. The PEM type cell configuration used for CO2 reduction in gas phase exhibited flow blockages in the cathodic compartment when using anolyte (KHCO3) concentrations above 0.1 M (combined with current densities over 8 mA/cm2). These obstruction troubles were attributed to the crossover of K+ across the cationic membrane and its possible combination with anions (mainly carbonate) to form precipitates in the cathodic flow channels. With Cu/CNT electrocatalyst it has been observed that CO2 conversion rate increases with CO2 flowrate in the range studied (0.02 to 0.08 SL/min). Temperature up to 80 ºC also seem to favor CO2 electroreduction in the gas phase configuration studied. Nevertheless, a maximum in the 2 CO2 conversion rate has been observed at a current density of 16 mA/cm . The use of Cu commercial nanoparticles impregnated on CNT has also been tested. The electrocatalytic activity of Cu/CB and Cu/rGO has been compared to that of Cu/CNT in the electrochemical reduction of CO2 in the PEM type cell. It has been observed that Cu/CNT attains CO2 conversion rate more than 30 % higher than Cu/rGO catalyst and almost double than Cu/CB. However, although the metallic content of these Cu based catalysts is very similar, Cu nanoparticle crystallite size varies among 13 and 19 nm in the catalysts, attending to XRD analysis. Thus, the difference among the CO2 conversion rates of the catalysts becomes smaller if they are normalized by active surface area. The CO2 conversion rate by active area with Cu/rGO differs less than 10 % from that with Cu/CNT. These results suggest that the interaction between Cu and the carbon support plays an important role on its catalytic activity. References (1) Barim, S.B.; Uzunlar, E.; Bozbag, S.E.; Erkey, C. J. Electrochem. Soc. 2020, 167, 054510.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Design and development of electrochemical sensors for the detection of nonelectroactive drugs of abuse: The amphetamine case

Noelia Felipe Montiel,a,b Marc Parrilla,a,b Filip Van Durme,c Karolien De Wael*,a,b

aAXES Research Group, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium. bNANOlab Center of Excellence, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium. cDrugs and Toxicology Department, National Institute for Criminalistics and Criminology (NICC), Vilvoordsesteenweg 100, 1120, Brussels, Belgium. [email protected] Amphetamine-type stimulants (ATS), a group of powerful central nervous system drugs, have been widely used for therapeutic purposes for several decades. Unfortunately, ATS long-term abuse has led to drug addiction and other serious side effects.1 Thus, their availability has been strictly regulated by authorities. Particularly, amphetamine (AMP) accounts for 5% of the total European Union seizures.2 Electrochemical sensors for illicit drug detection are becoming an emerging field in forensics due to their portability, affordability and accuracy which makes them suitable for on-site applications.3 Nevertheless, AMP electrochemical detection still remains a challenge due to the redox inactivity of its primary amine at carbon electrodes. Hence, an indirect detection method is required to unravel the presence of AMP in seizures. Herein, the rapid electrochemical oxidation of AMP in seized samples based on a labeling step with 1,2-naphthoquinone-4-sulfonate (NQS) is presented by using carbon screen-printed electrodes. An easy mixing process of the suspicious powder with carbonate buffer and NQS triggers the chemical reaction into an oxidizable product (Fig. 1). First, a detailed optimization of the key parameters and the analytical performance is provided. Then, the effect of NQS on common cutting agents is addressed. Interestingly, the comparison of the method with drugs- of-abuse containing secondary and tertiary amines confirms the selectivity of the method. Finally, the concept is applied in the detection of 20 seized samples provided by forensic laboratories. Overall, the fast and easy-to-use strategy is shown as a breakthrough for the screening of suspicious powders, aiming to facilitate the tasks of LEAs in the field.

Fig. 1. Schematics of the concept for the on-site screening of amphetamine.

(1) Berman, S. M.; Kuczenski, R.; McCracken, J. T.; London, E. D. Mol.Psychiatry 2009, 14 (2), 123–142. (2) European Monitoring Centre for Drugs and Drug Addiction. EU Drug Markets Report 2020; 2020. (3) Teymourian, H.; Parrilla, M.; Sempionatto, J. R.; Felipe Montiel, N.; Barfidokht, A.; Van Echelpoel, R.; De Wael, K.; Wang, J. ACS Sensors 2020, 5 (9), 2679-2700.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

CO2 electroreduction to formate on Sn, Bi, Sb nanostructured electrodes

Beatriz Ávila-Bolívar,a José Solla-Gullón,a Vicente Montiela

a Institute of Electrochemistry, University of Alicante, Apdo. 99, 03080 Alicante, Spain [email protected]

The electrochemical reduction of CO2 into chemical products of interest has been considered as an interesting route not only to mitigate climate change but also to store renewable energy in the form of value-added chemicals. Among other possible chemicals, formic acid (HCOOH) or formate (HCOO−) (depending on pH value) is one of the most attractive carbon-based products due to its potential uses and its high world demand including its use as a fuel for low- temperature fuel cells and as a renewable hydrogen carrier molecule. In this contribution, we will summarize our most recent and relevant results on the use of Tin (Sn), Bismuth (Bi), and Antimony (Sb) nanostructured based electrocatalysts for the selective conversion of CO2 into formic acid/ formate1–4. This summary will cover fundamental studies, including synthesis, characterization and electrochemical behaviour of these nanostructured materials on a conventional H-type electrochemical cell. Despite the good results of these nanomaterials as electrocatalysts for CO2 reduction, they also display some limitations regarding stability or activity. Recently, Sn, Bi or Sb alloys have shown be able to improve the electrochemical behaviour of these metals5,6. In this revision, we present our studies about this topic. We expect these findings can offer tips for designing metal alloy electrocatalysts with enhanced CO2 reduction performance.

Acknowledgements The authors of this work would like to acknowledge to the financial support from the MINECO, through the projects CTQ2016-76231-C2-2-R and PID2019-108136RB-C32 (AEI/FEDER, UE).

References (1) Del Castillo, A.; Alvarez-Guerra, M.; Solla-Gullón, J.; Sáez, A.; Montiel, V.; Irabien, A. J. CO2 Util. 2017, 18, 222–228. (2) Ávila-Bolívar, B.; García-Cruz, L.; Montiel, V.; Solla-Gullón, J. Molecules 2019, 24 (11). (3) Díaz-Sainz, G.; Alvarez-Guerra, M.; Solla-Gullón, J.; García-Cruz, L.; Montiel, V.; Irabien, A. J. CO2 Util. 2019, 34, 12–19. (4) Díaz-Sainz, G.; Alvarez-Guerra, M.; Ávila-Bolívar, B.; Solla-Gullón, J.; Montiel, V.; Irabien, A. Chem. Eng. J. 2021, 405, 126965. (5) Lucas, F. W. S.; Lima, F. H. B. ChemElectroChem 2020, 7 (18), 3733–3742. (6) Tian, J.; Wang, R.; Shen, M.; Ma, X.; Yao, H.; Hua, Z.; Zhang, L. ChemSusChem 2021, 14, 1-9.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Dual electrochemical immunoplatform for improving reliability in breast cancer diagnosis through the determination of RANKL and TNF in serum

A. Valverde,a V. Serafín,a A. Montero-Calle,b J. Gazoz,a A. González-Cortés,a M. Arenas,c J. Camps,c R. Barderas,b P. Yáñez-Sedeño,a S. Campuzano,a J.M. Pingarróna

a Faculty of Chemistry, Complutense University of Madrid, E-28040, Madrid, Spain. b UFIEC, Carlos III Health Institute, 28220, Majadahonda, Spain. c Institut d’Investigació Sanitària Pere Virgili, E-43204, Reus, Spain. [email protected]

Breast cancer (BC) is the second most common malignancy and a leading cause of death in women population. Among the different receptors used in classification of BC subtypes, human epidermal growth factor receptor 2 (HER2) exhibits a key role in tumor progression due to the correlation between HER2 protein overexpression or gene amplification with a more aggressive form of BC, frequently associated with metastatic events and unavoidably with the worst prognosis for the patient. Nevertheless, therapies based on hormonal treatments (i.e. Trastuzumab) have demonstrated to be the most effective way for transforming outcomes of HER2-subtype BC patients into one with a better prognosis. Therefore, detecting multiple cancer biomarkers implied in tumor progression, aggressiveness and metastatic event in BC patients and ideally closely related to the HER2-subtype has become a priority task in early diagnosis of this prevalent cancer in order to choose the most efficient therapy in the shortest time through fast, low-cost, portable and on-site monitoring methodologies.

This work describes a dual electrochemical immunoplatform using neutravidin-functionalized magnetic microbeads (Neu-MBs) and screen-printed dual carbon electrodes (SPdCEs) for the simultaneous amperometric determination of two relevant biomarkers related to the subtype and metastatic grade of BC: Receptor Activator of Nuclear Factor-κB Ligand (RANKL) and Tumor Necrosis Factor alpha (TNF). The developed methodology comprises sandwich-type immunocomplexes formed onto Neu-MBs using specific biotinylated capture, detector antibodies and HRP-labeled secondary antibodies, and performing the electrochemical detection by amperometry (-0.20 V vs. the Ag pseudo-reference electrode) with the H2O2/hydroquinone (HQ) system upon capturing the Neu-MBs modified with the sandwich immunocomplexes for each target biomarker on the corresponding working electrode (WE) of SPdCEs (1). The approach exhibits high sensitivity for the target proteins offering detection limits of 2.6 and 3.0 pg mL-1 for RANKL and TNF, respectively, using simple protocols and within a 90 min assay time. The usefulness of the dual immunoplatform was tested by determining RANKL and TNF levels in 5 µL of human serum from healthy individuals and BC patients diagnosed with different HER2 subtypes, showing a higher expression of both biomarkers in BC patients and higher correlated with the HER2 expression in the case of RANKL. These very relevant results from the clinical point of view, also in agreement to those provided by the ELISA methodologies for each individual target biomarker, reveal the potential of the developed immunoplatform to improve the reliability of BC diagnosis using fast and cost-effective procedures, compatible with its implementation in future Point-Of-Care testing (POCT) devices to perform rapid and decentralized routine determinations.

(1) Valverde et al.; Sens. Actuator B-Chem. 2020, submitted.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Photoelectrochemical energy storage: energy matching for an effective solar to chemical conversion

Teresa Andreu

University of Barcelona (UB). Dept. Materials Science and Physical Chemistry. C/Martí i Franquès, 1. 08028-Barcelona. Spain. [email protected]

The electrical conversion and storage of solar energy is crucial for assuring the world energy supply. Photoelectrochemical (PEC) energy storage devices offers the possibility to directly transfer the solar energy into several energy carriers, such as hydrogen, low-C fuels/chemicals from CO2 reduction or other redox pairs like batteries. In this contribution, it will presented our developments on integrated devices and fabrication of stable photoelectrodes. It will be discussed how impedance analysis (EIS) is a fundamental tool to understand the charge transfer and identify the main bottlenecks that could limit photoelectrode efficiency, specially for the oxygen evolution reaction (OER). Concerning the integrated devices, depending on the system, its design is not seamless unless the light-absorber photovoltage is customized to the voltage needs of the redox pairs. In the case of CO2 reduction, partial current polarization curves should be taken into account, since reaction selectivity usually depends on the applied potential under controlled photocurrent, which will depend on the solar irradiance. On the other hand, for PEC redox flow batteries, unlike artificial photosynthesis synthesis, the required photovoltage continuously increase with the state-of- charge. By using amorphous silicon tandem multijunction photocathodes, it has been demonstrated that for either CO2 reduction to syngas or solar vanadium redox flow batteries, an unbiased solar-to-chemical conversion efficiency 10% is achievable. Each technology will have in the future its niche market, while the solar-to-electricity roundtrip is more favorable for redox flow devices than for hydrogen or solar fuels, there is an urgent need to decarbonize our chemical industry with green hydrogen and upcycled CO2.

The work was funded by MINECO projects WINCOST (ENE2016-80788-C5-5-R) and CCU+OX (PID2019-108136RB-C33).

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Electrochemical DNA-based biosensor for monitoring CRISPR-Cas12 activity: Detection of Listeria monocytogenes

a a a Hugo Cunha-Silva, Elisa Jiménez, and Félix Amárita

a AZTI, Food Research, Basque Research and Technology Alliance (BRTA). Parque Tecnológico de Bizkaia, Astondo Bidea, Edificio 609, 48160 Derio - Spain. [email protected]

The limiting factor in the detection of pathogens by molecular methods is the need of getting sufficient genetic starting material, that is obtained by means of enrichment cultures in time consuming processes. The advances in molecular biology techniques, allow to perform genomic amplification in a faster and more efficient way. However, it still lacks the required sensitivity to obviate the enrichment step. In this sense, the food industry demands rapid methods that allow to reduce this time-consuming phase, aiming to achieve a faster availability of the products to the market. The tremendous advances on the genetic editing techniques based on Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), opened doors to new strategies in the analytical field. When coupled to endonucleases like Cas12 and associated with specific nucleic acid probe (guide RNA), the system CRISPR/Cas12 is able to recognize and cut the target DNA, becoming active to cut single strand oligonucleotides in a nonspecific manner. CRISPR/Cas systems have been recognized to detect attomolar concentrations of nucleic acids, being an excellent alternative to decrease the times required for pathogens detection (1). One of the most problematic pathogens for the food industry is Listeria monocytogenes (L. monocytogenes). European regulation in force establishes that foods in which, due to their characteristics, the growth of Listeria monocytogenes is favored, must not present more than 100 CFU/g during their shelf-life. Early detection through time and cost-effective analytical approaches is a must (2). In this work, we have developed a DNA-based electrochemical biosensor to detect the trans- cleavage activity of CRISPR/Cas12 when activated by the presence of L. monocytogenes. The biosensor was mounted using a screen-printed gold electrode (SPAuE) and immobilized single strand DNA (ssDNA) tagged with a methylene blue (MeB) redox probe (ssDNA-MeB). When CRISPR/Cas12 is incubated onto the electrode, at 37°C and in presence of DNA from L. monocytogenes, the immobilized oligonucleotides are cut, and the cathodic signal of MeB is decreased. To improve the electrode performance, the SPAuE was submitted to cleaning steps and to blockage of the electroactive surface to avoid unspecific adsorption. The application of a cathodic stripping square wave voltammetry (CSSWV) allows to detect minimal differences of MeB redox signal, related to the concentration of L. monocytogenes. The application of this DNA-based biosensor allows to detect L. monocytogenes concentrations bellow to 50 CFU/mL in lysate extracts.

References (1) Chan, J.S.; Ma, E.; Harrington, L.B.; Da Costa, M.; Tian, X; Palefsy, J.M.; Doudna, J.A., Science 2018, 360(6387), 436-439. (2) Soni, D.K.; Ahmad, R.; Dubey, S.K., Critical Reviews in Microbiology 2018, 44, 5.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Charge transfer in nanostructured composite materials: a photoelectrochemical approach.

Javier Hernández-Ferrer, Emin Istif, Alejandro Ansón-Casaos, Ana Santidrián, Ana M. Benito, Wolfgang K. Maser

Instituto de carboquímica-CSIC, c/ Miguel Luesma Castán 4, 50018 Zaragoza, Spain [email protected]

Photoelectrochemical techniques are accurate for the study of intrinsic electronic properties of a great variety of nanostructured semiconductor materials, such as conductive polymers, carbon nanomaterials (GO, CNTs, CDs) or metal oxide nanoparticles. It is also a highly valuable implement to assess charge and/or energy transfer phenomena between the mentioned semiconductors unveiling their role as charge acceptors/donors, blockers/transporters, sensitizers/conditioners, or even as photoelectroactive materials for themselves, thus allowing the tuning of optoelectronic properties of composite materials, for their future application in fields related to energy and environment, such as water splitting, electronics, solar cells or water remediation. This versatility makes photoelectrochemistry a key tool in the field of nanoscience and nanotechnology 1-4. CdS 0 nm B 0.0 C 4 f-MoS2 A 0.16 5 nm -0.5 2 MoS -CdS 0.14 10 nm 2 0 0.12 20 nm A -1.0  60 nm  -2 0.10 -1.5 -2

A -4

-2.0  / cm 0.08 I ꞏ -6 0.06 -2.5

/mA P3HT j NPs -8 -3.0 0.04 P3HTNPs-GO (C3)

Photocurrent -10 P3HT -GO (C2) 0.02 -3.5 NPs P3HT -GO (C1) -12 -4.0 NPs 0.00 -14 -0.02 -4.5 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 -0.6 -0.4 -0.2 0.0 0.2 0.4 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 E(vs Hg/HgO, 0.1 M KOH)/V Potential/ V E(Ag/AgCl)/V Figure 1. Photoelectrochemical properties of TiO2/electrochemically reduced GO (A), P3HT/GO composites (B) and MoS2-CdS composites (C).

(1) Istif, E., Hernández-Ferrer, J., Urriolabeitia, E.P., Stergiou, A., Tagmatarchis, N., Fratta, G., Large, M.J., Dalton, A.B., Benito, A.M., Maser, W.K. Advanced Functional Materials ,2018, 28, Article number 1707548 (2) Hernández-Ferrer, J., Ansón-Casaos, A., Víctor-Román, S., Sanahuja-Parejo, O., Martínez, M.T., Villacampa, B., Benito, A.M., Maser, W.K. Electrochimica Acta 298, 2019, 279 (3) Hernández-Ferrer, Ansón-Casaos, A., Víctor-Román, S., Santidrián, A., Benito, A.M., Maser, W.K. Journal of Electroanalytical Chemistry, 2018, 828, 86 (4) Santidrián, A., González-Domínguez, J.M., Diez-Cabanes, V., Hernández-Ferrer, J., Maser, W.K., Benito, A.M., Ansón-Casaos, A., Cornil, J., Da Ros, T., Kalbáč, M. Physical Chemistry Chemical Physics, 2019, 21, 4063

Acknowledgements. MINECO and AEI/FEDER/UE (project ENE2016-79282-C5-1-R), European Union (H2020-MSCA- ITN-2014-ETN 642742), Gobierno de Aragón (Grupo Reconocido DGA T03_17R, FEDER/UE).

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Monitoring the H2O2 released by elicited living plant cells with modified SPCEs in complex culture medium and aerobic conditions

Rebeca Jiménez Pérez,a Lorena Almagrob, María Isabel González-Sáncheza, María Ángeles Pedreñob and Edelmira Valeroa.

a Department of Physical Chemistry, Higher Technical School of Industrial Engineering, University of Castilla-La Mancha, Campus Universitario s/n, 02071, Albacete, Spain. b Department of Plant Biology, Faculty of Biology, University of Murcia, Campus de Espinardo, E-30100, Murcia [email protected]

Monitoring hydrogen peroxide in living cells is of great significance for understanding its functions since it plays a crucial role as a signalling molecule in various physiological processes. Knowing the amount of H2O2 produced by plant cells under stress conditions may be helpful in developing a better understanding of tolerance mechanisms to oxidative stress and thus to improve the levels of cell growth and the production of bioactive compounds. Aerobic conditions and a medium which provides cells with the necessary nutrients are required to ensure cell survival and make their long-term study possible. However, to the best of our knowledge, most studies conducted with electrochemical sensors have been usually obtained in phosphate buffer and many of them have been performed in N2-saturated media. These conditions would not be compatible with studying cellular behavior for long times. Besides, it has been proven that the oxidation potential of H2O2 in phosphate-buffered saline (PBS) is subjected to a marked shift of the signal towards higher potentials in complex cell suspensions 1. Our research group recently demonstrated that the combined use of a conjugated polymer with platinum nanoparticles on a previously activated disposable electrode, displays excellent 2 analytical performance toward H2O2 monitoring . Based on this study we have developed a non-enzymatic H2O2 sensor based on Pt nanoparticles electrogenerated on a film of poly(azure A) supported in a SPCE (Pt@PAA(DS)/aSPCE). This sensor proved to be very sensitive and selective to the detection of H2O2 even in complex media. Pt@PAA(DS)/aSPCE has been used to investigate the dynamic process of H2O2 release from living plant cells (Vitis vinifera cv. Monastrell) over prolonged periods of time and under different (a)biotic stresses. All experiments have been carried out in supplemented Gamborg B5 culture medium and aerobic conditions, which makes this sensor a promising tool for H2O2 sensing in living cells under real conditions.

References (1) Marcu, R.; Rapino, S.; Trinei, M.; Valenti, G.; Marcaccio, M.; Pelicci, P. G.; Paolucci, F.; Giorgio, M. Bioelectrochemistry 2012, 85, 21-28 (2) Jiménez-Pérez, R.; González-Rodríguez, J.; González-Sánchez, M.-I.; Gómez- Monedero, B.; Valero, E. Sensors Actuators B Chem. 2019, 298,126878.

Funding sources: Projects PID2019-106468RB-I00 (AEI/FEDER, UE) from MINECO, SBPLY/17/180501/000276/2 (cofounded with FEDER funds, EU) from JCCM (Junta de Comunidades de Castilla-La Mancha), and 19876/GERM/15 from Fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia (Spain).

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Degradation of Diazinon based on PEC technique using enhanced WO3 nanostructures

G. Roselló-Márquez,a R. M. Fernández-Domene,a,b R. Sánchez-Tovar,a,b M. Cifre-Herrando.a J. García-Antóna

a Ingeniería Electroquímica y Corrosión (IEC), Instituto Universitario de Seguridad Industrial, Radiofísica y Medioambiental (ISIRYM), Universitat Politècnica de València, C/Camino de Vera s/n, 46022, Valencia, Spain b Departamento de Ingeniería Química, Universitat de Valencia, Av de les Universitats, s/n, 46100, Burjassot, Spain [email protected]

The necessity to control and eliminate emergent contaminants in the environment has become increasingly crucial during the last decades. So, in this work, we have degraded a resistant and toxic pesticide called diazinon through the photoelectrocatalysis (PEC) technique using tungsten oxide (WO3) nanostructures, applying a potential of 1 VAg/AgCl and simulated solar illumination. PEC is attracting the attention of researchers due to its capacity to degrade organic pollutants into harmless compounds with non-extreme working conditions. This technique requires the use of semiconductors for its proper operation and WO3 is an n-type semiconductor with many advantages, such as its high chemical stability in low pH values, non- photoelectric corrosion and its ability to absorb a reasonable fraction of the solar spectrum. In this study, WO3 nanostructures have been synthesized using electrochemical anodization in acidic electrolytes. In order to improve the properties of WO3 nanostructures, two acids have been used during the anodization in the presence of very low amounts of hydrogen peroxide: 1.5 M H2SO4- 0.05 M H2O2 and 1.5 M CH4O3S- 0.05 M H2O2. With the aim of analyzing accurately and of comparing the properties of both samples, Field Emission Scanning Electron Microscopy (FE-SEM) and Raman Spectroscopy have been used to study the morphology and composition and crystallinity, respectively. Then, by Photo- Electrochemical Impedance Spectroscopy (PEIS), the photoelectrochemical properties of the electrodes interface was compared. The nanostructures obtained with 1.5 M CH4O3S - 0.05 M H2O2 electrolyte presented better photoelectrochemical properties than nanostructures synthesized in 1.5 M H2SO4- 0.05 M H2O2. To conclude the research work, the degradation process was checked by UV-Visible and through Ultra High-Performance liquid Chromatography and Mass Spectrometry (UHPLC- MS-Q-TOF) we have controlled the course of the experiments and identify possible degradation intermediates.

Acknowledgments Authors thank AEI (PID2019-105844RB-I00/ AEI/10.13039/501100011033) for the financial support and, as well, to E3TECH under project CTQ2017-90659-REDT (MINECO, Spain). G. Roselló-Márquez and M. Cifre-Herrando also thanks the Generalitat Valenciana for the concession of a pre-doctoral grant (ACIF/2018/159 and ACIF/2020/229). Finally, project co- funded by FEDER operational programme 2014-2020 of Comunitat Valenciana (IDIFEDER/18/044) is acknowledged.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Nanostructured Sensing Platforms Based on the Use of Ternary Complexes as Electrocatalysts

M. Revenga-Parraa,b,c , A. M. Villa-Mansoa , E. Lorenzo a,b,c, F. Pariente a,b,c aDepartamento de Química Analítica y Análisis Instrumental, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain. bInstitute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain. cInstituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Faraday, 9, Campus UAM, Cantoblanco, 28049 Madrid, Spain. [email protected]

Ortho-quinones have been described as potent and efficient electrocatalysts, especially when are deposited or polymerized onto solid electrodes. In this way, several ortho-quinone derivatives have been employed successfully as powerful electrocatalysts able to reduce of the large overpotential observed for the electroxidation of different compounds such as hydrazine or NADH. Taking in account these electrochemical properties, electrodes modified with quinone derivatives are continuously under study. In this sense, hematein, oxidized form of hematoxylin, has been extensively used as a histochemical dye. Hematein has a intramolecular charge-transfer chromophoric system in which two quinone/hydroquinone domains are involved. The dihydroxybenzene domain acts as electron donor while benzoquinone domain acts as acceptor. In addition, the presence of these groups provides hematein the ability to form metal complexes. In this sense, the most studied one is the ternary complex formed with the aluminum ion (III) because it is the basis of one of the most used methods in histology for staining cellular genetic material (chromatin). Taking advance of these properties, in this work a new strategy to modify screen-printed graphene electrodes, based on the formation of a ternary complex composed of double-stranded DNA, aluminum ion and the histochemical dye hematein, has been developed. Modification of the electrodes was carried out in two stages: firstly, by direct deposition of dsDNA and aluminum ion on the graphene surface of the electrodes, and secondly, by electrodeposition of hematein over them. Optimal conditions for electrodeposition were studied. The resulting modified electrode was characterized by cyclic voltammetry, confirming the presence of the characteristic quinone/hydroquinone moieties. The scanning electron microscopy reveals that the electrode surface is covered by spongy structures, correspond to spherical nanoparticles that join together forming branches due to the formation of the aforementioned complex on the surface of the electrode. This novel nanostructured platform presents a good stability and it has been used to construct sensing devices based on the powerful properties of Ortho-quinones as catalysts. As a proof of concept, the electrocatalytic activity of the sensor towards the oxidation of hydrazine has been extensively studied in this work. Hydrazine, a highly corrosive, irritating and toxic substance, has been widely used in industry and aerospace. Therefore, the large-scale application of this compound and its derivatives involves a great risk to the environment and humans. For this reason, there is a great interest in the development of sensitive and selective analysis methods capable of determining traces of hydrazine in a sample easily and quickly. The good results obtained have opened the possibility of employ other nanomaterials, instead of DNA, to form ternary complexes with hematein using different metals as mordant in order to develop sensing platforms with improved analytical properties.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Simultaneous Electrochemical Removal of Nitrate and Terbuthylazine Pesticide from Low-Conductivity Groundwater

Roger Oriol, Enric Brillas, Pere L. Cabot, Francesc Centellas, and Ignasi Sirés

The great intensification of agricultural and farming activities over the last decades has entailed the accumulation of different types of organic and inorganic pollutants in aquifers. Some of the former ones are classified as contaminants of emerging concern (CEC) due to the uncertain toxic effects. The pesticide terbuthylazine (TBA) has become ubiquitous in the EU, being frequently detected in natural water. TBA and its main by-product desethyl-terbuthylazine (DET) are toxic towards aquatic organisms and act as endocrine disruptors, but are only partially removed by conventional water treatments.1 On the other hand, pig farming involves the generation of large volumes of swine wastewater. Its disposal is currently under strict control (Spanish Real Decreto 980/2017), since it is a major source of nitrate in groundwater. In recent years, several technologies have been developed for the removal of refractory organic pollutants. Electro-oxidation (EO) stands out among the eco-friendly electrochemical advanced oxidation processes (EAOPs) as the simplest method, with high ability to produce hydroxyl radicals (OH) adsorbed on the anode surface. Coupling a high efficient anode for EO with a suitable electrocatalytic cathode that allows the simultaneous nitrate electroreduction in groundwater has been the aim of this work. This is not a straightforward task, since such water has low conductivity and contains Mg(II) and Ca(II) ions that can precipitate on the cathode surface, eventually causing its fouling. In practice, this results in an excessive cell voltage increase that makes the treatment not economically viable. This communication reports the performance of an electrochemical system developed on the basis of our previous studies.2,3 The cell consisted of two mesh electrodes, i.e, Nb/BDD anode and Fe cathode, separated 3 mm to treat 500 mL of solutions containing 5 mg L-1 of TBA and about 100 mg L-1 nitrate. The experiments were carried in different water matrices: (i) simulated groundwater, mimicking the main characteristics of an actual groundwater, and (ii) the actual groundwater, which has been conveniently softened prior to the electrolyses. Large percentages of both, denitrification and EO, were attained, and the reaction products were characterized.

References (1) Tasca, A.L.; Puccini, M.; Fletcher, A. Chemosphere 2018, 202, 94. (2) Oriol, R.; Bernícola, P.; Brillas, E; Cabot, P.L.; Sirés, I. Electrochim. Acta 2019, 317, 753. (3) Oriol, R.; Clematis, D.; Brillas, E.; Cortina, J.L.; Panizza, M.; Sirés, I. ChemElectroChem 2019, 6, 1235. Acknowledgments Financial support from PID2019-109291RB-I00 (AEI, Spain), as well as the PhD scholarship awarded to R. Oriol (MINECO, Spain) are acknowledged.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Development of an electrochemical method for the detection of peroxides in air samples

Rebeca Jiménez-Péreza, Rubén López-Corredora, María Teresa Baeza-Romerob, Jesús Iniestac, Edelmira Valeroa

aDepartment of Physical Chemistry, Higher Technical School of Industrial Engineering, University of Castilla-La Mancha (UCLM), 02071-Albacete, Spain. bDepartment of Physical Chemistry, School of Industrial and Aerospace Engineering, UCLM, 45004-Toledo, Spain. cDepartment of Physical Chemistry and Institute of Electrochemistry, University of Alicante, 03690, San Vicente del Raspeig, Alicante, Spain. [email protected]

Air pollution is nowadays a very serious and important scientific issue as it has a wide-ranging impact on the whole environment. Aerosols, also called particle matter (PM), are liquid or solid particles suspended in the air. Organic material makes a major contribution to the mass of fine PM in the atmosphere, being Secondary Organic Aerosol (SOA) the most significant contributor. SOA are organic aerosols generated within the atmosphere from primary emissions. It is a highly complex organic mixture still poorly characterized. Model simulations predict organic hydroperoxides to be the major contributors of SOA mass [1]. These compounds are key components of SOA that determine its optical properties and hence their importance for climate change. Additionally, they constitute a health risk because of their high reactivity and oxidation potential. The most widely used techniques to measure peroxides in environmental atmospheric samples are based on High Performance Liquid Chromatography (HPLC) coupled with fluorescence detection, enzyme-based assays, mass spectrometry, and iodometry (the latter one for total peroxide content). However, all these methods present some kinds of drawbacks. In recent years, electrochemical sensors have demonstrated a great potential to measure peroxides, and thus they arise as proposed analytical tools for effective environmental monitoring. Lately, we have developed a highly sensitive non-enzymatic sensor for H2O2 [2], based on poly(Azure A)- Pt nanoparticles (PtNPs/PAA) deposited on previously activated screen printed carbon electrodes (aSPCEs) [3]. In this work we explored the performance of this modification protocol on different screen-printed carbon electrodes as a proof-of-concept of organic peroxides detection. Analytical outcomes are quite promising so they deserve further work for the electrochemical sensing of organic peroxides in SOA.

References (1) Johnson, D.; Jenkin, M.E.; Wirtz, K.; Martin-Reviejo, M. Environ. Chem., 2004, 1, 150-165. (2) Jiménez-Pérez, R.; Gonzalez-Rodriguez, J.; González-Sánchez, M.I.; Gómez- Monedero, B.; Valero, E. Sensor Actuat. B-Chem. 2019, 298, 126878. (3) González-Sánchez, M.I.; Gómez-Monedero, B.; Agrisuelas, J.; Iniesta, J.; Valero, E. Electrochem. Commun. 2018, 91, 36-40.

Funding sources: Projects PID2019-106468RB-I00 (AEI/FEDER, UE) and PID2019- 108136RB-C32 from MINECO, and SBPLY/17/180501/000276/2 (cofounded with FEDER funds, EU) from JCCM (Junta de Comunidades de Castilla-La Mancha) (Spain).

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Heterogeneous electro-Fenton at a bench-scale reactor for the treatment of clofibric acid

V. Poza-Nogueiras,a A. Moratalla,b M. Pazos,a M.A. Sanromán,a C. Sáez,b and M.A. Rodrigob

a Chemical Engineering Department, University of Vigo, Isaac Newton Building, As Lagoas- Marcosende, 36310 Vigo (Spain) b Chemical Engineering Department, University of Castilla-La Mancha, Enrique Costa Novella Building, Av. Camilo José Cela nº 12, Ciudad Real (Spain) [email protected]

Since conventional wastewater treatments have demonstrated to be inefficient for the elimination of recalcitrant organic pollutants, electrochemical advanced oxidation processes have acquired increasing relevance. Among those processes, electro-Fenton (EF) treatment has been widely investigated. It relies on the formation of ꞏOH through the catalytic decomposition of in situ generated hydrogen peroxide in the presence of the ferrous ion. However, research on EF process is frequently performed at a laboratory scale, and only few studies are focused on a future industrial application (1). Therefore, this work aims at carrying out EF tests at a bench- scale reactor for the degradation of a persistent pharmaceutical and pesticide: clofibric acid.

The proposed system is formed by a jet aerator which introduces the required oxygen to form H2O2 at the cathode without the need of a compressor; a microfluidic flow-through electrochemical cell with two 3D electrodes; and a fluidized bed where a solid catalyst for the Fenton reaction is placed. Altogether, these elements provide a reactor configuration that allows an efficient production of H2O2, reducing the mass transfer limitations and energy consumption (2), and benefiting from the advantages of using a heterogeneous catalyst.

Several experiments have been performed in the described system, using a boron-doped diamond electrode as the anode, a titanium mesh painted with a mixture of carbon black and PTFE as the cathode and iron alginate beads as the catalyst. Different current densities (2.5 and 5 mA cm-2) and relative pressures (0, 1 and 2 bar) were tested, analyzing the effect of those parameters on the production of H2O2 and the degradation of clofibric acid. The obtained results showed that the bench-scale reactor is capable of achieving an efficient elimination of the compound under study, observing an enhancement in the degradation of the pollutant and a reduction in the specific energy consumption when working above atmospheric pressure.

Acknowledgements: Authors would like to acknowledge the financial support of the Spanish Ministry of Science, Innovation and Universities and ERDF Funds (CTM2017-87326-R), the Excellence Network E3TECH (CTQ2017-90659-REDT) and Junta de Comunidades de Castilla-La Mancha (SBPLY/17/180501/000396). Poza-Nogueiras thanks the support of a PhD fellowship (FPU16/02644) and a mobility action funded by the University of Vigo.

References (1) Casado, J. Journal of Environmental Chemical Engineering 2019, 7, 102823. (2) Pérez, J.F.; Llanos, J.; Sáez, C.; López, C.; Cañizares, P.; Rodrigo, M.A. Journal of Cleaner Production 2019, 211, 1259-1267.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Multivariate curve resolution by alternating least squares combined with the standard addition method for the quantification of substances producing overlapping voltammetric signals

José Manuel Díaz-Cruz,a,b, María A. Tapiaa, Clara Pérez-Ràfolsa, Núria Serranoa,b, Cristina Ariñoa,b

a Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, 08028-Barcelona, Spain. b Water Research Institute (IdRA), University of Barcelona. [email protected]

A multivariate version of the classical univariate standard addition method is proposed for the voltammetric analysis of samples producing overlapping signals in the presence of notorious matrix effects. Unlike previous versions, based on the subtraction of the signal measured for the sample 1, the use of second order data2 or multivariate calibration by partial least squares (PLS)3, the proposed strategy takes advantage of a self-modelling methodology: multivariate curve resolution by alternating least squares (MCR-ALS) enhanced with signal shape constraints based on parametric functions4. Among the parametric signals tested, the simple and symmetric peak provided by Gaussian function exhibited the best performance to work with differential pulse voltammograms (DPV). In contrast, asymmetric peak functions typically used in MCR-ALS showed a good fitting but also a dangerous trend to neglect small signals and incorporate them to the queue of large signals. As compared to PLS methodology, the application of MCR-ALS to standard addition measurements does not need the full multivariate response of a blank solution. Moreover, in multianalyte determinations, the standard additions can be made using a solution containing all the analytes, which constitutes a clear advance as compared to previous approaches. The proposed method has been validated with simulated data and has been further applied to the voltammetric determination of the isomers hydroquinone and catechol by DPV with graphene screen-printed electrodes in solutions of increasing complexity. The good results obtained suggest that the combination of MCR-ALS with Gaussian signal shape and the standard addition approach could be a promising tool in the field of electroanalysis.

References

(1) Saxberg, B. E.; Kowalski, B. R. Anal. Chem. 1979, 51, 1031–1038. (2) Lozano, V. A.; Tauler, R.; Ibañez, G. A.; Olivieri, A. C. Talanta 2009, 77, 1715–1723. (3) Martínez, K.; Ariño, C.; Díaz-Cruz, J. M.; Serrano, N.; Esteban, M. Chemom. Intell. Lab. Syst. 2018, 178, 32–38. (4) Tapia, M. A.; Pérez-Ràfols, C.; Ariño, C.; Serrano, N.; Díaz-Cruz, J. M. Anal. Chem. 2020, 92, 3396–3402.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Study of use of sodium hydroxide produced in a Chlor-Alkali cell to reduce carbon footprint using a new spraying system

Mireya Carvela Solera, Alexandra Raschitora, Justo Lobato Bajoa and Manuel Andrés Rodrigo Rodrigoa a University of Castilla-La Mancha, Chemical Engineering Department. Av. Camilo Jose Cela n 12, Enrique Costa Novella Building, Ciudad Real (13071) Spain [email protected]

Nowadays, global warming is one of the most important issue worldwide. The main cause is the progressive accumulation of carbon dioxide (CO2) in the atmosphere, from a large number of human activities, mainly industrial. For this reason, one of the most relevant concerns for the scientific community in recent years has been the search for methods to reduce this gas, which is the main cause of the greenhouse effect (CO2) (1). Our work proposes a way to reduce CO2 using sodium hydroxide (NaOH) resulting from the chemical process that takes place during the operation of a reversible Hydrogen-Chlorine cell. Specifically, the use of NaOH produced during chlor-alkaline electrolysis is proposed to transform CO2 into carbonates, reducing the amount of this gas and obtaining a product useful for the chemical industry (2).

In our research, we propose a new way to produce carbonates from carbon dioxide through the use of sodium hydroxide resulting from the operation of a reversible cell, whose purpose is to obtain and store clean energy. In summary, we are developing the use of a Hydrogen-Chlorine cell with two modes of operation: in the first one, chlor-alkaline electrolysis is carried out, and in the second, electrical energy is produced from the products obtained from the electrolysis (hydrogen and chlorine). This procedure ensures that the proposed cell model is considered reversible and allows a continuous cycle of energy production and storage. During this process, specifically in the electrolysis mode, NaOH is generated as a result of the reduction reactions that take place in the electrochemical cell. For this reason, in order to take advantage of this residual product, a system of conversion of CO2 into carbonates has been developed (3). This system uses a column with diffusers that allow the spraying of NaOH to supply its reaction with CO2. This technology allows a more efficient carbonate production than other processes seeking the same objective, since the spraying of NaOH allows a very high use of the sodium contained in sodium hydroxide in its reaction with CO2.

(1) Shim, J-G.; Lee, DW.; Lee, JH; Kwak, N-S. Environmental Engineering Research 2016, 21(3), 297-303. (2) Yoo, M.; Han, S-J.; Wee, J-H; Kwak, N-S. Journal of Environmental Management 2013, 114, 512-519. (3) Stolaroff, J.K.; Keith, D.W.; Lowry, G.V. Environmental Science & Technology 2008, 42 (8), 2728-2735.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Molecular Recognition with Gold (111) Electrodes Modified with Mixed Nucleolipid/Phospholipid Monolayers

Francisco Prieto Dapenaa, ZhangFei Sub, Estrella Dragoa, Julia Alvarez Malmagroa,b, Manuela Rueda, Jacek Lipkowskib

a Department of Physical Chemistry, University of Seville, C/Professor García González n◦ 2, 41012 Seville, Spain. b Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1. [email protected]

Nucleolipid molecules consist in a phospholipid covalently bonded by its polar head to a nucleoside or to a nucleotide. Monolayers of nucleolipids at the air water interphase have exhibited molecular recognition capabilities to the complementary DNA base of the nucleolipid, when it is present in the aqueous subphase. In recent works, we have prepared supported monolayers of 1,2-dipalmitoyl-sn-glycero-3-(cytidine diphosphate) nucleolipid (DG-CDP) on gold (111) electrodes and shown their capability to recognize the complementary base, guanine, when the monolayer had been incubated in the presence of guanine: photon polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) revealed the existence of the Watson-Crick cytosine:guanine complex.1 The stability of lipidic monolayers is favored by the lateral hydrophobic interactions between adjacent acyl chains. DG-CDP and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) have identical acyl chains. However, the Langmuir isotherms corresponding to monolayers of DG-CDP and monolayers of DPPC show that the minimum area per molecule in the DG-CDP monolayer is higher than in the DPPC monolayer and, therefore, the lateral interactions between acyl chains are weaker in the nucleolipid monolayer. Electrostatic, H-bond and/or steric interactions between the polar heads of nucleolipid must be responsible for this phenomena in the monolayer.2 In this work, we have studied mixed monolayers of DG-CDP/DPPC at the air/water and air/electrolyte interfaces with different mole fractions. The thermodynamic analysis permitted us to select the optimum composition of the mixture, minimizing the repulsive interactions between polar heads of nucleolipid molecules while maintaining the maximum reactivity to guanine recognition. The mixed monolayer with this optimum composition has been transferred to gold (111) electrodes, in order to characterize it and to investigate its molecular recognition capabilities to guanine by electrochemical and ‘in-situ’ PM-IRRAS measurements.

References (1) Alvarez-Malmagro, J.; Su, Z.; Leitch, J. J.; Prieto, F.; Rueda, M.; Lipkowski, J. Electric-Field-Driven Molecular Recognition Reactions of Guanine with 1,2- Dipalmitoyl-Sn- Glycero -3-Cytidine Monolayers Deposited on Gold Electrodes. Langmuir 2019, 35 (28), 9297–9307. https://doi.org/10.1021/acs.langmuir.9b01238. (2) Alvarez-Malmagro, J.; Su, Z.; Jay Leitch, J.; Prieto, F.; Rueda, M.; Lipkowski, J. Spectroelectrochemical Characterization of 1,2-Dipalmitoyl- Sn-Glycero-3-Cytidine Diphosphate Nucleolipid Monolayer Supported on Gold (111) Electrode. Langmuir 2019, 35 (4), 901–910. https://doi.org/10.1021/acs.langmuir.8b03674.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Thursday July 08th, 2021,

8h15 - 9h00 Plenary Lecture : José Luis Tirado (Room 24) (chair: Carlos Sanchez Sanchez)

9h00 - 10h15 Session 1

Room 24 (chair:Nuria Garcia Araez) Room 34A(chair:Eduardo Laborda) J.A.Coca Clemente J.M. Feliu J. Carretero Gonzalez R. Rizo E. Garcia Gaitan A. Gonzalez Orive Antonio Molina R. Madueño E. Mundaray-Guilarte J.L. Olloqui Sariego

10h15 - 10h45 Coffee break 10h45 - 12h30 Session 2

Room 24 (chair:F.J. Recio) Room 34A (chair:Ricardo Souto) X.R. Novoa J. Gonzalez L. Lopez Chalarca T. Binninger J.J. Garcia Jareño A. Boudet C. Mariño Martinez M. Brites Helu J. Izquierdo J. Fernandez Vidal Belen Diaz J. Garcia Cardona B. Hernandez Concepcion Y. Holade

12h30 - 14h00 Lunch

14h00 - 15h30 Sponsors and Poster Sessions

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Room 24 (chair: Neus Vila) Room 34A (chair:Carlos Sanchez Sanchez) ORIGALYS HTDS P01-P32 P33-P66

15h30 - 16h Coffee break 16h00 - 17h Session 3

Room 24 (chair:Cristina Saez) Room 34A (chair: Jose Solla Gullon) E. Mousset E. Pastor J.M. Ortiz B. Oraa J.J. Lado M. Gonzalez Ingelmo G. Sanchez Obrero M. Perez Estebanez

17h00 - 18h30 Master Programs presentation (chair: E. Torralba)

Fethi Bedioui-ChimieParisTech-FR Christine Cachet-Vivier-UPEC-FR Victor Climent-Universidad Alicante- SP Emmanuel Maisonhaute- Sorbonne Univ.-FR Neus Vila Cusco- Univ. Lorraine-FR

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

From Li-ion batteries to recent dual-ion alternatives

Saúl Rubio, Alejandro Medina, Rafael Klee, Marta Cabello, Pedro Lavela, Ricardo Alcántara, Carlos Pérez Vicente, Gregorio F. Ortiz, José L. Tirado

Departamento de Química Inorgánica e Ingeniería Química, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUNAN, Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, España. [email protected]

In 2019, the scientific community specialized in the field of electrochemical energy storage received with great joy the Nobel Prize in Chemistry, awarded to Prof. M. Stanley Whittingham, Prof. John B. Goodenough, and Prof. Akira Yoshino, for the development of lithium-ion batteries. Since 1990, Li-ion batteries have extended their use to more and more demanding applications, such as EV and HEV, and the efficient use of intermittent renewable energy sources. The forecast of an extensive battery application to avoid the use of fossil fuels and their effect on global warming has generated serious concerns about the performance, safety, and sustainability of Li-ion batteries. A post-Li-ion era has been postulated, in which dual-ion batteries are among other possibilities. Two different strategies fall within this category. On the one hand, dual(cation-anion) systems involve both ions in the electrochemical reactions (1-2). In dual-metal-ion (hybrid) systems, two different metal ions participate in ether metal anode or rocking-chair systems, delivering interesting synergies (3-4). The advantages of sodium concerning its abundance and availability make Na-ion batteries a strong alternative, particularly for stationary applications (5). However, other abundant multivalent elements such as Mg and Al may provide higher energy densities. The use of dual-Mg-Na-ion batteries has been suggested to fully exploit the benefits of a moderately priced metal Mg anode combined with low-cost sodium salts. Different Na-Mg dual designs have shown high efficacy by Na+/Mg2+ co-intercalation and improved energy density, safety, rate capability, and cycling stability (6-8). In this presentation, recent results on dual-metal-ion systems, including vanadium oxide and phosphate electrodes, are discussed.

References (1) Santhanam, R.; Noel, M. J. Power Sources 1998, 76, 147. (2) Seel, J. A.; Dahn, J. R. J. Electrochem. Soc. 2000, 147, 892. (3) Yao, H.-R.; You, Y.; Yin, Y.-X.; Wan, L.-J.; Guo, Y.-G. Phys. Chem. Chem. Phys. 2016, 18, 9326. (4) Zhang, Y.; Shen, J.; Li, X.; Chen, Z.; Cao, S.; Li, T.; Xu, F. Phys. Chem. Chem. Phys. 2019, 21, 20269. (5) Palomares, V.; Serras, P.; Villaluenga, I.; Hueso, K. B.; Carretero-González J.; Rojo, T. Energy Environ. Sci. 2012, 5, 5884. (6) Walter, M.; Kravchyk, K. V.; Ibañez, M.; Kovalenko, M.V. Chem. Mater. 2015, 27, 7452. (7) Li, Y.; An, Q.; Cheng, Y.; Liang, Y.; Ren, Y.; Sun, C.; Dong, H.; Tang, Z.; Li, G.; Yao, Y. Nano Energy 2017, 34, 188. (8) Bian, X.; Gao, Y.; Fu, Q.; Indris, S.; Ju, Y.; Meng, Y.; Du, F.; Bramnik, N.; Ehrenberg, H.; Wei, Y. J. Mater. Chem. A 2017, 5, 600.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Improvement of Lithium Metal Polymer Batteries through a Small Dose of Fluorinated Salt

José A. Coca-Clemente,a Alexander Santiago,a Xabier Judez,a Julen Castillo,a Iñigo Garbayo,a Amaia Sáenz de Buruaga,a Lixin Qiao,a Giorgio Baraldi,a Michel Armand,a Chunmei Li,a Heng Zhanga

Introducing a small dose of an electrolyte additive into solid polymer electrolytes (SPEs) is an appealing strategy for improving the quality of the solid electrolyte interphase (SEI) layer formed on the lithium metal (Li°) anode, thereby extending the cycling life of solid-state lithium metal batteries (SSLMBs). In this work, we report a new type of SPEs comprising a low-cost, fluorine-free salt, lithium tricyanomethanide (LiTCM), as the main conducting salt and a fluorinated salt, lithium bis(fluorosulfonyl)imide (LiFSI), as the electrolyte additive for enhancing the performance of SPE-based SSLMBs. Our results demonstrate that a homogeneous and stable SEI layer is readily formed on the surface of the Li° electrode through the preferential reductive decomposition of LiFSI, and consequently, the cycle stabilities of Li°||Li° and Li°||LiFePO4 cells are significantly improved after the incorporation of LiFSI as an additive. The intriguing chemistry of the salt anion revealed in this work may expedite the large-scale implementation of SSLMBs in the near future.

(1) Santiago, A; Judez, X.; Castillo, J.; Garbayo, I.; Sáenz de Buruaga, A.; Qiao, L.; Baraldi, G.; Coca-Clemente, J. A.; Armand, M.; Li, C.; Zhang, H. J. Phys. Chem. Lett. 2020, 11, 6133−6138. (2) Zhang, H.; Judez, X.; Santiago, A.; Martinez-Ibañez, M.; Muñoz-Márquez, M. Á.; Carrasco, J.; Li, C.; Eshetu, G. G.; Armand, M. Adv. Energy Mater. 2019, 9 (25), 1900763. (3) Aldalur, I.; Martinez-Ibañez, M.; Piszcz, M.; Rodriguez-Martinez, L. M.; Zhang, H.; Armand, M. J. Power Sources 2018, 383, 144−149.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Efecto de la carga superficial en la reducción de oxígeno sobre electrodos de platino

Juan M. Feliua Valentín Briega-Martosa y Enrique Herreroa

a Instituto de Electroquímica. Universidad de Alicante. Apartado 99. E-03080 Alicante. España. [email protected]

Se ha investigado el comportamiento del peróxido de hidrógeno, que es un posible intermedio de la reacción de reducción de oxígeno (ORR), sobre electrodos de platino que contienen terrazas iguales, de simetría (111), separadas por escalones monoatómicos de simetría (110) y (100) en medios de distinto pH (1). Sobre estos electrodos se observa una disminución en valor absoluto de la corriente de reducción a potenciales bajos, que se puede correlacionar con el potencial de máxima entropía (pme) de la formación de la doble capa en las terrazas. Además, es posible relacionar el potencial del pico que aparece a potenciales inferiores a 0.3 V (RHE) con el pme local en los escalones. Al realizar experimentos a distintos valores de pH, hasta pH ≈ 5, se ve que el potencial de inhibición en las terrazas se desplaza 59 mV por cada unidad de pH hacia potenciales más positivos, conforme a lo observado para el pme en experimentos de salto de temperatura inducidos por láser. Para la posible explicación de este fenómeno hay que tener en cuenta que la adsorción de OH puede influir en esta tendencia cuando los valores de pme estén cerca de los potenciales correspondientes a la adsorción de OH. A partir de resultados obtenidos en medio alcalino, se puede argumentar que la influencia de la carga superficial en la estructura del agua juega un papel importante en esta inhibición de la corriente límite de difusión. Finalmente, la comparación de los resultados obtenidos en condiciones similares para la reducción del peróxido de hidrógeno y del oxígeno sugiere que la formación de peróxido de hidrógeno como intermedio de la ORR está menos favorecida al aumentar el pH. Como consecuencia, debe existir una bifurcación en el mecanismo de la ORR anterior a la formación de peróxido. Estos resultados coinciden con otros anteriores (2), que señalan que la ORR implica distintas etapas en las que pueden existir diversos puntos de bifurcación. Dependiendo de las condiciones experimentales, la reacción puede optar por una ruta de reacción diferente (3).

Referencias (1) Briega-Martos, V.; Herrero, E.; Feliu, J.M. Electrochimica Acta 2020, 334, 135452. (2) Gomez-Marin, A.M.; Feliu, J.M. ChemSusChem 2013, 6, 172-176. (3) Briega-Martos, V.; Herrero, E.; Feliu, J.M. Chinese J. Catal. 2020, 41, 732-738.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Innovative redox active polymeric nanomaterials as potential low-cost electrolytes for sustainable flow batteries

A. Fernández-Benitoa, F. J. Rivera-Gálveza,b, P. Navalpotroa, D. Arenas-Estebanc, D. Ávila-Brandec, C. F. Jasso-Gastinelb, M. D. Hagerd, U. S. Schubertd, M. Á. López-Manchadoa and J. Carretero-Gonzáleza

a Institute of Polymer Science and Technology, ICTP-CSIC, Madrid, Spain b Chemical Engineering Department, Universidad de Guadalajara, Guadalajara, México c Department of Inorganic Chemistry, Universidad Complutense de Madrid, Madrid, Spain d Center for Energy&Environmental Chemistry, Friedrich Schiller Univ. Jena, Jena, Germany [email protected]

Herein we will describe a series of innovative nanostructured polymers exhibiting high redox activity and water solubility so then being potential low-cost, rechargeable electrolyte materials for aqueous flow electrochemical devices. One of the novel systems consists of nanoparticles comprising innocuous and functional (including redox) interpenetrated macromolecular networks. Another family of electrolytes is based on amphiphilic block-copolymer micelles with a fine-tuned chemical composition to boost capacity and water solubility. A complete study of the physical, chemical and electrochemical properties of these advanced nanostructured functional polymeric materials will be presented and the results derived are discussed in the scope of their potential application as rechargeable electrolyte materials for redox flow batteries.

References

(1) Goodenough J. B.; Energy Environ. Sci. 2014, 7, 14–18. (2) Soloveichik G. L.; Annu. Rev. Chem. Biomol. Eng. 2010, 2, 503–527W. (3) Carretero-González J.; Castillo-Martinez E.; Armand M.; Energy Environ. Sci. 2016, 9, 3521-3530.

Acknowledgment

J.C.G. acknowledges support from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) through a Ramon y Cajal Fellowship (RYC-2015-17722) and the Retos Project (MAT2017-86796-R, AEI/FEDER/UE). D.A.E. and D.A.B acknowledge the Retos Project (MAT2017-84385-R, AEI/FEDER/UE). P.N. acknowledges the postdoctoral contract from the Government of the Comunidad de Madrid (CAM, PEJD-2018-POST/AMB- 9248). Financial support from Excellence Network E3TECH under project CTQ2017-90659- REDT (MINECO, Spain) is also acknowledged.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Nuevas perspectivas en la reacción de reducción de peróxido de hidrógeno y su comparación con la reacción de reducción de oxígeno sobre superficies bien definidas de Pt en medio alcalino

Rubén Rizoa, Juan M. Feliua, Enrique Herreroa

aInstituto de Electroquímica, Universidad de Alicante, Apdo. 99, E-03080, Alicante, Spain. [email protected]

En trabajos recientes demostramos la gran influencia que tiene la carga superficial y el agua interfacial en las reacciones de reducción de oxígeno (RRO) y peróxido de hidrógeno (RRPH), lo que afecta al mecanismo para ambas reacciones [1]. Sin embargo, el estudio de la estructura superficial del electrodo en la RRPH en medio alcalino (pH = 13) y su comparación con el RRO [2], aún debe explorarse en detalle. Para dicha finalidad, la RRPH se ha investigado en medio alcalino en los tres planos basales de Pt así como en diferentes superficies escalonadas de Pt con terrazas (111) separadas por escalones monoatómicos (100) o (110). En dicho estudio, se ha observado que la actividad para la RRPH disminuye progresivamente al aumentar la densidad de sitios (110) y /o (100) pasos (Figura 1). Por otro lado, se observa una inhibición de la HPRR a potenciales bajos. El valor de potencial de inicio de esta inhibición viene dominado tanto por la adsorción de OH sobre la superficie como por el punto de máxima entropía (pme) de la interfase. Experimentos adicionales, demostraron la existencia de un intermedio formado durante la HPRR, que se adsorbe más fuertemente sobre sitios (110) que en sitios (100), y el cual está vinculado al proceso de inhibición. Finalmente, se estudiaron las importantes diferencias existentes entre la RRPH y la RRO, asociadas a las diferentes interacciones de los intermedios adsorbidos, así como del propio O2 con la superficie.

4,0 A) Pt (111) B) Pt (111) 3,0 Pt(151514) Pt (171515) Pt (776) Pt(544) 2,0 Pt(554) Pt (533) Pt(775) Pt(211) 1,0 Pt (331) Pt(311) -2 0,0

-1,0 j / mA cm -2,0

-3,0

-4,0

0,20,40,60,81,01,2 0,2 0,4 0,6 0,8 1,0 1,2 E / V vs. RHE Figure 1. Curvas de polarización durante el barrido negativo para la RRPH/ROPH en NaOH 0.1 M y H2O2 a 2 mM sobre las superficies Pt(S)[(n-1)(111) × (110)] (A) y Pt(S)[(n)(111) × (100)] (B); velocidad de barrido: 50 mV s−1, velocidad de rotación: 2500 rpm

References [1] Briega-Martos, V; Herrero E; Feliu J.M.; Electrochim. Acta 2020, 334, 135452-13562. [2] Rizo, R.; Herrero, E.; Feliu, J.M.; Phys. Chem. Chem. Phys. 2013, 15, 15416–15425.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Naturally-derived biopolymer electrolyte for Zn-air batteries

E. García-Gaitán,a,b,c Maria C. Morant-Miñana,a A. Bustinza,a I. Cantero,b D. González,b and N. Ortiz-Vitorianoa,d

a Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, 01510, Miñano, Spain b CEGASA Energía SLU, Marie Curie, 1, Parque Tecnológico de Álava, 01510 Miñano, Spain c University of the Basque Country (UPV / EHU), Barrio Sarriena, s / n, 48940 Leioa, Spain d Ikerbasque, Basque Foundation for Science, María Díaz de Haro 3, 48013, Bilbao, Spain [email protected] High energy demand and concerns about climate change have urgently promoted a transition from fossil fuels to clean renewable energy. Rechargeable lithium batteries, currently on the market, are at their fever pitch and are a good alternative to fossil fuels. However, its use in stationary energy storage systems involves a great cost, being necessary to seek new highly competitive technologies at lower cost. In this sense, Zn-air batteries are attracting a great deal of attention thanks to: (1) Zn abundance in the earth's crust which is one of the most abundant minerals; (2) high energy density (6136 W h L-1) and a relatively high specific energy (1218 Wh kg-1); (3) low cost and (4) operational safety. [1] Currently, Zn-air batteries present leakage or evaporation of the alkaline liquid electrolyte due to its open system, which causes a decrease in the performance and short cycle life. [2, 3] However, this drawback can be overcome by the use of solid electrolytes. The development of an emerging solid electrolyte, based on a natural, linear, and biodegradable polymer will be presented. The biopolymer soaked in a saline solution forms a suitable gel to be used as a solid electrolyte, which also works as a separator in Zn-air batteries. In this study, its manufacture and characterization will be presented, as well as its electrochemical performance in a Zn-air battery. This novel electrolyte presents a conductivity of 4.5x10-1 Sꞏcm-1 similar to the commonly used liquid KOH electrolyte (8M KOH solution presents a conductivity of 6.1x10-1 Sꞏcm-1). [4] The electrochemical testing in a Zn-air battery shows excellent performance and higher Zn-extraction when compared with other solid electrolytes. Acknowledgments This project (RTC-2017-6238-3 AEI / FEDER, EU) is funded by the Ministry of Economy and Competitiveness and by the European Regional Development Fund FEDER. E. Garcia thanks the Basque Government for the Beca Bikaintek 01-AF-W2-2019-00003. References (1) Fu, J.; Cano, Z. P.; Park, M. G.; Yu, A.; Fowler, M.; Chen, Z. Advanced Materials 2017, 29 (7), 1604685. (2) Gu, P.; Zheng, M.; Zhao, Q.; Xiao, X.; Xue, H.; Pang, H. Journal of Materials Chemistry A 2017, 5 (17), 7651–7666. (3) Mainar, A.; Leonet, O.; Bengoechea, M.; Boyano, I.; De Meatza, I.; Kvasha, A.; Guerfi, A.; Alberto Blázquez, J. International Journal of Energy Research 2016, 40 (8), 1032–1049. (4) See, D. M.; White, R. E. Journal of Chemical and Engineering Data 1997, 42 (6), 1266– 1268.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Electrically transmissive alkyne anchored monolayers on gold

Alejandro González-Orive,a Lucía Herrer,b,c Santiago Marqués-González,d Santiago Martín,b,e Alberto Hernández-Creus,a Richard J. Nichols,f José Luis Serrano,b,c Paul J. Low,g and Pilar Ceab,c,e

a Área de Química Física, Departamento de Química, Facultad de Ciencias, Universidad de La Laguna (ULL), Instituto de Materiales y Nanotecnología (IMN), 38200 La Laguna, Tenerife, Spain b Departamento de Química Física, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain c Instituto de Nanociencia de Aragón (INA) and Laboratorio de Microscopias Avanzadas (LMA), edificio i+d Campus Río Ebro, Universidad de Zaragoza, C/Mariano Esquillor, s/n, 50018 Zaragoza, Spain d Department of Chemistry, Durham University, South Rd, Durham, DH1 3LE, UK e Instituto de Ciencias de Materiales de Aragón (ICMA), Universidad de Zaragoza- CSIC, 50009 Zaragoza, Spain f Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK g School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia

[email protected]

The self-assembly of 1,4-bis((4-ethynylphenyl) ethynyl)benzene (1) on gold results in well- ordered and tightly-packed monolayered films, as deduced from high-resolution images taken with atomic force microscopy (AFM) and scanning tunneling microscopy (STM), with the subsequent formation of alkynyl C–Au σ-bonds, as demonstrated by Surface-enhanced Raman spectroscopy (SERS). Not too many reports have dealt so far with direct Au-C anchoring groups for molecular junctions studies.1 The anodic and cathodic electrochemical desorption of 1 is also explored. Cyclic voltammetry measurements employing different redox probes indicate that the as-prepared ethynyl C–Au contacted monolayer of 1 exhibits a relatively low barrier for electron transfer. This contrasts with monolayered films of other oligo(phenylene ethynylene) moieties incorporating different contact groups, but showing comparable length and surface coverage. The molecule conductance of 1 has been characterized by means of the 2 “STM touch-to-contact” method. A low voltage transition (Vtrans = 0.51 V) from direct tunneling (rectangular barrier) to field emission (triangular barrier) is observed. This low transition voltage hints at a low tunneling barrier, which is consistent with the facile electron transport observed through the C–Au contacted self-assembled monolayer of 1. References 1. (a) Fu, Y.; Chen, S.; Kuzume, A.; Rudnev, A.; Huang, C.; Kaliginedi, V.; Baghernejad, M.; Hong, W.; Wandlowski, T.; Decurtins, S.; Liu, S.-X., Exploitation of desilylation chemistry in tailor-made functionalization on diverse surfaces. Nature Communications 2015, 6, 6403; (b) Moneo, A.; González-Orive, A.; Bock, S.; Fenero, M.; Herrer, I. L.; Milan, D. C.; Lorenzoni, M.; Nichols, R. J.; Cea, P.; Perez-Murano, F.; Low, P. J.; Martin, S., Towards molecular electronic devices based on ‘all-carbon’ wires. Nanoscale 2018, 10 (29), 14128-14138. 2. Ballesteros, L. M.; Martín, S.; Marqués-González, S.; López, M. C.; Higgins, S. J.; Nichols, R. J.; Low, P. J.; Cea, P., Single Gold Atom Containing Oligo(phenylene)ethynylene: Assembly into LB Films and Electrical Characterization. The Journal of Physical Chemistry C 2015, 119 (1), 784-793.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Redox- Active Conjugated Microporous Polymer based on Anthraquinone for High-Performance Lithium-Ion Batteries

Antonio Molina, a Nagaraj Patil a, Edgar Ventosa a, Marta Liras b, Jesús Palma a, and Rebeca Marcilla a*

aElectrochemical Processes Unit, IMDEA Energy, Avda. Ramón de la Sagra 3, 28935 Móstoles, Spain bPhotoactivated Processes Unit, IMDEA Energy, Avda. Ramón de la Sagra 3, 28935 Móstoles, Spain [email protected]

In the last two decades the develop and research of Lithium ion batteries (LIBs) has been greatly increased. Nowadays, LIBs are dominated by carbon composite electrodes and inorganic intercalation compounds which often contains toxic and scarce metals such cobalt or nickel. Even though their success in commercial LIBs, there is a need for cost-effective, large scale, environmentally friendly, sustainable and safer electrode materials. One of the best alternatives are organic electrodes and specifically redox-active polymers (RAPs)1. These materials have extraordinary properties such as, environmentally friendly, cheap, abundant and can be obtained from natural sources. Furthermore, RAPs present high theoretical capacity, tunable redox potential and fast kinetics which make it ideal for battery use. Among huge variety of RAPs, here we present our recent research on Conjugated Microporous Polymers (CMPs) having redox functionalities as excellent candidates for battery electrodes. Redox-active conjugate microporous polymer (RCMPs) were synthesized by addition of anthraquinone redox-active building block into the conjugated 3D polymer structure. In this talk we will discuss on the synthesis of anthraquinone-based RCMPs by combining miniemulsion polymerization method as a strategy to get nanostructured polymers easy to process as high performing electrodes. We investigate the effect of synthesis conditions on the physico-chemical and electrochemical properties of obtained polymers. We demonstrated that RCMPs synthesized by miniemulsion technique combine excellent redox behavior due to antraquinoyl redox groups, fast charge transport due to π-conjugated backbone, fast ion mobility due to porous structure and extraordinary (electro)chemical stability over cycling due to the shape-persistent 3D microporous nature2. All these characteristic increased the battery performance as longevity, service life and enhanced redoxactive sites utilization and thus higher capacity.

1 S. Muench, A. Wild, C. Friebe, B. Häupler, T. Janoschka and U. S. Schubert, Chem. Rev., 2016, 116, 9438–9484. 2 A. Molina, N. Patil, E. Ventosa, M. Liras, J. Palma and R. Marcilla, Adv. Funct. Mater., 2019, 1908074, 1908074.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Phase transitions of 6-(Ferrocenyl)hexanethiol layers on gold

Rafael Madueño a, Victoria Carnero, Guadalupe Sánchez, José M. Sevilla, Manuel Blázquez, Teresa Pineda

a Departamento de Química Física y T.A., Instituto de Química Fina y Nanoquímica, Universidad de Córdoba, Campus de Rabanales, Ed. Marie Curie 2ª planta, E-14014 Córdoba, España [email protected]

Surface-tethered layers of redox-active molecules are important to design “smart” interfaces and build electrically addressable systems for applications in photo- and electrocatalysis, sensing, and information storage.1-3 Ferrocene monolayers have been widely used as a model system for studying charge transfer across molecular interfaces to electrodes. In this sense, optimal design and control of electrochemically switchable interfaces, based on using ferrocene moieties, requires fundamental understanding of the structural and dynamic factors affecting electron transfer kinetics in such redox-active organic adlayers.4

Organic adlayers can undergo orientation transformations and/or structural phase transitions driven by potential change.5 These dynamical processes may be triggered by electric fields, surface charges, and/or a redox reaction. Thus, the interplay of molecule-substrate and/or short- range intermolecular interactions with surface charge density; including the rearrangement of solvent molecules and interfacial ions, greatly contributes to modulate such processes. 2D faradaic phase transitions are often recognized by current spikes in cyclic voltammetry (CV) during the interconversion of the oxidations states, and by the presence of transient current maxima in chronoamperometric curves ascribed to 2D nucleation and growth mechanisms.5 However, non-faradaic current transitions may still apply in parallel to the faradaic ones, as a result of double layer charging, adsorption, condensation and reorientation of dipoles at the electrified interface. The present work aims to study phase transitions of 6- (Ferrocenyl)hexanethiol layers adsorbed on gold, which are formed from an ethanol solution and subsequently rinsed with different solvents. The process is characterized by CV, chronoamperometry, EIS and capacitance curves under different experimental conditions (e.g. temperature and scan rate dependence).

Acknowledgements: We thank the Ministerio de Educación y Ciencia (Project RED2018- 102412-T Network of Excellence Electrochemical Sensors and Biosensors), Junta de Andalucía and Universidad de Córdoba (UCO-FEDER-2018: ref. 1265074-2B and Plan Propio, SUBMOD. 1.2. P.P. 2019) for financial support of this work.

References 1. Khan, A.; et.al., Research advances in the synthesis and applications of ferrocene-based electro and photo responsive materials. Applied Organometallic Chemistry 2018, 32 (12), e4575. 2. Hein, R.; Beer, P. D.; Davis, J. J., Electrochemical Anion Sensing: Supramolecular Approaches. Chemical Reviews 2020, 120 (3), 1888-1935. 3. Welker, M. E., Ferrocenes as Building Blocks in Molecular Rectifiers and Diodes. Molecules 2018, 23 (7). 4. Calvente, J. J.; Andreu, R., Intermolecular interactions in electroactive thiol monolayers probed by linear scan voltammetry. Current Opinion in Electrochemistry 2017, 1 (1), 22-26. 5. Madueno, R.; Pineda, T.; Sevilla, J. M.; Blazquez, M., Formation and dissolution processes of the 6-thioguanine (6TG) self-assembled monolayer. A kinetic study. Journal of Physical Chemistry B 2005, 109 (4), 1491-1498.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Acid-Base Electrochemical Flow Battery Using Neutralization Energy

Eleana Mundaray-Guilarte,a Alfonso Sáez,a José Solla-Gullón,a Vicente Montiel a

aInstituto de Electroquímica, Universidad de Alicante. Apdo. 99, E-03080, Alicante, Spain

[email protected]

The development of clean, renewable and affordable energy sources as a consequence of global warming has become a necessity for society. Consequently, the development of devices capable of efficiently storing the energy obtained from these sources is highly required. In this sense, Hydrogen-based technologies have become a promising candidate both as fuel and transmission element. [1].

A redox flow battery is an electrochemical energy storage device that converts chemical energy into electrical energy through reversible oxidation and reduction of working fluids [2]. Based on this concept an Acid-Base Electrochemical Flow Battery (ABEFB) has been developed. This system is composed of acidic and alkaline solutions, both with a high supporting electrolyte concentration, which are separated by a cationic exchange membrane. Hydrogen oxidation and evolution reactions take place during the charge and discharge processes, which acidifies or basifies the corresponding electrolytes. The neutralization energy obtained from these solutions is used as electromotive force [3]. In this case, HCl and NaOH are used as electrolytes, NaCl as supporting electrolyte, a platinised Pt electrode as cathode, a Pt-catalysed gas diffusion electrode as anode (catalyst loading of 0.5 mg cm-2) and a cationic membrane as ionic separator.

In this work, the effect of the supporting electrolyte concentration, the state of charge, and the nature of cationic membrane have been systematically studied. Polarization curves and charge/discharge cycles were obtained to evaluate the performance of the system. We found that this battery can provide a maximum power density of 10.6 mW cm-2 at 27.5 mA cm-2, and a coulombic efficiency of around 80 %, depending on the H+/Na+ ratio and the membrane thickness. This study reveals a promising energy-storage system, with simple operation and low cost.

References [1] Midilli, A.; Dincer, I. Hydrog. Energy, 2007, 32, 511-524. [2] Vanýsek, P.; Novák, V. J Energy Figure 2:a) Polarization curves and power curves for Storage, 2017, 13, 435-441. 0.3, 0.5 and 1.0 M HCl/NaOH, with 2.0 and 4.0 M [3] Sáez, A.; Montiel, V. Hydrog. Energy, NaCl. b) Charge/discharge cycles for a charge 2016, 41, 17801-17806. capacity of 3350 mAh, at 12.5 mA cm-2

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Revisiting the Proton-Coupled Electron Transfer of Immobilized Iron Porphyrins

Inmaculada Márquez, José Luis Olloqui-Sariego, Miguel Molero, Rafael Andreu, Emilio Roldán and Juan José Calvente

Departamento de Química Física, Universidad de Sevilla, c/Profesor García González, 1, 41012-Sevilla, Spain. [email protected]

The combined study of the redox and acid/base properties of iron porphyrins is important to understand the effect that exerts both the oxidation state of the metal center and the ionization state of the ionizable groups, on the coordinative chemistry of the heme group.1 The quantification of the proton transfers coupled to the electron transfer event is useful to identify the factors that control the redox potential of the heme group (and hemoproteins), and to rationalize conformational changes induced by the exchange of ionizable ligands.2 The interfacial electron transfer of metalloporphyrins is generally coupled to protonation / deprotonation processes involving their ionizable groups,3 to avoid an accumulation of charge at the interface or simply to stabilize one of the redox states involved in the process. In the presence of certain ligands, the electron transfer can also be coupled with association processes between the metal center and ligands. Under these conditions, the electrochemical response provides information on the thermodynamics of these processes. Motivated by the discrepancy of the titration curves reported in literature for immobilized iron porphyrins, herein, we have revisited the effect of the solution pH on the voltammetric features of two iron porphyrins, differing in their β substituents, immobilized onto electrodes. It has been found that their proton-coupled electron transfer is accompanied by binding events with the electrolyte components, which provokes a deviation from the expectations of a 1e-/1H+ transfer. A theoretical strategy has been developed to quantify the pKa values of the corresponding redox-dependent ionizable groups in the presence of ionic binding. The obtained results reveal an increase of the acidity of the iron-bound water molecule upon replacing β alkyl substituents by propionic acid residues in the porphyrin ring.4

References (1) Warren, J. J.; Mayer, J. M. J. Am. Chem. Soc. 2011, 133, 8544–8551. (2) Alvarez-Paggi, D.; Hannibal, L.; Castro, M. A.; Oviedo-Rouco, S.; Demicheli, V.; Tórtora, V.; Tomasina, F.; Radi, R.; Murgida, D. H. Chem. Rev. 2017, 117, 13382– 13460. (3) De Groot, M. T.; Koper, M. T. M. Phys. Chem. Chem. Phys. 2008, 10, 1023– 1031. (4) Márquez I.; Olloqui-Sariego J. L.; Molero, M.; Andreu A.; Roldán E.; Calvente J. J. Inorg. Chem. 2021, 60, 42-54.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Characterisation of commercial Li-ion batteries using EIS

I. Ezpeletaa, L. Freireb, A. Pintosa, C. Mateo-Mateob, X. R. Nóvoaa, and S. Valverdea

a ENCOMAT group, Universidade de Vigo, EEI. 36310 Vigo, Spain b Centro Tecnológico AIMEN. 36418 O Porriño, Spain [email protected]

Battery management systems (BMS) are commonly employed to manage packs of identical cells that form a battery. The main task of a BMS is to manage the battery pack so that it can provide high amount of energy maintaining overall high performance[1]. The aim is to maximize the life and ensure a safe operating point. For this task complete cell monitoring is required, which includes energy management during charging and discharging, temperature control and battery impedance parameters estimation with the aim of obtaining the different states: state of charge (SoC), state of health (SoH) and state of functionality (SoF, available charging and discharging power). We present here an EIS based method[2] for identification of the battery impedance parameters that informs about the charge transfer and diffusion processes at both electrodes. The model developed reproduces adequately the experimental spectra, as shown in Fig. 1, for 0% SoC and two operation temperatures

Z' / mW

Fig. 1: Experimental and fitted impedance spectra corresponding to a cylindrical cell (400 cm2 developed surface) at 0% SoC and 5 and 25 °C.

References [1] Fleischer, C.; Waag, W.; Heyn, H. M.; Sauer, D. U. On-Line Adaptive Battery Impedance Parameter and State Estimation Considering Physical Principles in Reduced Order Equivalent Circuit Battery Models: Part 1. Requirements, Critical Review of Methods and Modeling. J. Power Sources, 2014, 260, 276–291. [2] Guitián, B.; Nóvoa, X. R.; Pintos, A. EIS as a Tool to Characterize Nanostructured Iron Fluoride Conversion Layers for Li-Ion Batteries. Bulg. Chem. Commun., 2018, 50 (Special Issue D), 82–89.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Evaluation of kinetic parameters of surface confined redox species in presence of intermolecular interactions by using Cyclic Voltammetry.

Joaquin Gonzalez, Jose-Alfonso Sequí Departamento de Química Física, Facultad de Química, Regional Campus of International Excellence “Campus Mare Nostrum”, Universidad de Murcia, 30100 Murcia, Spain [email protected]

The tailored design of electrochemical interfaces or devices based on surface confined electroactive molecules for an specific purpose is strongly conditioned by their redox functionality. This redox functionality is based on a sequence of relevant charge transfer processes and is determined by, among other factors, the value of the electrochemical rate constant of the same, which can be strongly influenced by the medium in which it takes place. There exists a variety of different electrochemical methods for the measurement of the electrochemical rate constant and other related variables. The method most frequently employed is Cyclic Voltammetry, for which, based on Laviron’s ideal model, the rate constant is obtained from the shift of the voltammetric peak potentials in terms of the scan rate [1]. This methodology, although broadly used, present several limitations. For example, it needs the a priori assumption of a given kinetic formalism, typically the Butler-Volmer (BV) one. Moreover, it does not consider the influences of non-idealities, and therefore lead to a simplistic description of the voltammetric responses that in many practical situations does not coincide with the experimental results [2, 3]. A first approach to achieve a more accurate description of the electrochemical behaviour of modified interfaces is to consider the existence of intermolecular interactions of repulsive or attractive nature. The causes of these interactions are related with the appearance of coulombic long range repulsions, or with the presence of attractive Van der Waals interactions (i. e., odd- even) or π-π interactions, among others [3]. The influence of interactions is quantized through two potential-independent interaction parameters, G and S, introduced by Laviron, among other authors, when considering a Frumkin type of adsorption isotherm [1, 4]. In this communication, we analyze the influence of the above parameters on the methods for obtaining accuracy values of the kinetic rate constants of surface confined redox probes. A discussion is done concerning the deviations observed, which can lead to significant errors in the values obtained when these deviations are not considered. The above methods have been applied to the characterization of different redox probes under non-ideal conditions.

Acknowledgements Fundación Séneca - Agencia de Ciencia y Tecnología Región de Murcia (19887/GERM/15)

References (1) Laviron, E.; Roullier, L., J. Electroanal. Chem. 1980, 115, 65. (2) Bizzotto, D.; Burguess, I. J.; Doneux, T.; Sagara, T.; Yu, H-Z, ACS Sensors 2018 3 5 (3) Calvente, J. J.; Andreu, Curr. Op. Electrochem., 2017, 1, 22. (4) Gonzalez, J.; Sequi, J. A., ACS Omega 2018, 3, 1276

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

NaNiF3 perovskite as conversion electrode for sodium-ion battery.

Liliana T. López Ch.,a FranklinJaramilloa, Jorge A. Calderóna, and Jose L.Tiradob aCentro de Investigación, Innovación y Desarrollo de Materiales-CIDEMAT, Facultad de Ingeniería, Universidad de Antioquia, Medellín, Colombia. bLaboratorio de Química Inorgánica, Universidad de Córdoba, Córdoba, Spain. [email protected]

Sodium-ion battery has emerged as an attractive technology for energy storage of smart electric grids and renewable resources because of the enormous availability of sodium and its low cost of production. The main restriction of sodium ion in comparison to lithium-ion batteries is its lower energy density.Therefore, in the present days, different electrode materials have been explored to increase the capacity of those batteries. Particularly, the perovskite structure is an attractive material due to its novel properties in different aspects such as mobility, ionic conductivity, low cost, facile route of synthesis, and fabrication. Sodium-metal-fluoride perovskites as NaMF3 (M: Fe, Ni, Cu, Mn, Mg, V, Co) have been reported on sodium-ion 1,2 application . NaFeF3 electrode was explored as cathode material and showed a capacity c.a. 250 mAhg-1 between a voltage window of 4.5-1.5 V, and the mechanism of the reaction was 3 proven to be an intercalation process . On the other hand, NaNiF3 was reported with a capacity -1 of 50 mAhg in a similar voltage window than the NaFeF3 electrode. It also worked as active cathode material and the mechanism seems to be an intercalation process. However, NaNiF3 could also have a conversion type behavior with a theoretical capacity of c.a. 380 mAhg-1. In this work, we obtained NaNiF3 perovskite as electrode material in sodium-ion battery on nickel foam as a current collector into a voltage window of 0.01-4V. The process started by discharge to lead to the conversion reaction. Here a remarkable capacity of c.a. 210 mAhg-1 was obtained with retention of c.a. 40% over 30th cycles and global coulombic efficiency around 100%, as showed in Figure 1.

4.0

3.5

(V) 3.0 +

2.5 Cycle 1 Cycle 2 2.0 Cycle 3 1.5 Cycle 4 Cycle 5 1.0 Cycle 10 Cycle 20 0.5 Cycle 30 Voltage vs. Na/Na 0.0 0 20 40 60 80 100 120 140 160 180 200 220 -1 Specific capacity (mAhg ) + Figure 1. Capacity of NaNiF3perovskite electrode material vs Na/Na References (1) Kitajou, A.; Ishado, Y.; Yamashita, T.; Momida, H.; Oguchi, T.; Okada, S. Electrochim. Acta2017, 245, 424. (2) Gocheva, I. D.; Nishijima, M.; Doi, T.; Okada, S.; Yamaki, J. Ichi; Nishida, T. J. Power Sources2009, 187, 247. (3) Yamada, Y.; Doi, T.; Tanaka, I.; Okada, S.; Yamaki, J. I. J. Power Sources2011, 196, 4837.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Classical and Quantum Characteristics of the Capacitance of Electrode–Electrolyte Interfaces in Joint Density Functional Theory

Tobias Binningera

a ICGM, Univ. Montpellier, CNRS, ENSCM, Montpellier, France [email protected]

The ab initio simulation of charged interfaces using density functional theory (DFT) is highly relevant for the study of electrochemical energy conversion processes. Implicit approaches to model the electrolyte side of the electrode–electrolyte interface were cast into a solid theoretical framework by joint density functional theory (JDFT) that provides a combined description of both the electronic density of the electrode and the ionic and dielectric densities of the electrolyte. The electronic properties of the electrode material affect its electrochemical behavior, giving rise to the so-called quantum capacitance CQ that is essentially equal to the electronic density of states (DOS). Typically, it is assumed that the quantum capacitance acts in series with the "classical" double-layer capacitance Cdl, resulting in the generally employed partitioning of the total interfacial capacitance, 1/Ctot = 1/CQ + 1/Cdl. However, in spite of its fundamental relevance, the motivation for this partitioning appears to be rather heuristic so far.

I will present an approach [1] that allows to rigorously derive both quantum and classical characteristics of the capacitance of complex electrode–electrolyte interfaces ab initio from JDFT. Whereas the quantum capacitance arises from the DOS of the Kohn-Sham single-particle orbitals, the double-layer capacitance is determined by the interaction between the local density of states (LDOS) of the electrode and the Fukui function of the electrode–electrolyte system. Importantly, we precisely obtain the serial partitioning of the total interface capacitance, including an additional capacitive contribution due to the electronic exchange-correlation interaction. The derived relation reveals the influence of the electrode material, thickness, and temperature, which is particularly relevant for thin electrodes where all capacitive contributions are significant. Moreover, the presented approach provides a clear understanding of the transition from thin two-dimensional electrodes to the limit of thick bulk electrodes where the well-known classical capacitive response is recovered. This insight will be illustrated by computational results for bulk and single-layer gold electrodes, and a single-layer graphene electrode.

References (1) Binninger, T. Phys. Rev. B 2021, 103, L161403.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Digital video electrochemistry applied to the study of Prussian Blue films

J. J. García-Jareño, I. Coloma, J. Agrisuelas, E. Guillén, and F. Vicente

Departament de Química Física, Universitat de València. C/ Dr. Moliner, 50, 46100, Burjassot, València, Spain [email protected]

Prussian Blue films electrodeposited on a Pt disc electrode surface were studied by cyclic voltammetry and in situ digital video electrochemistry. Derivative Red color intensity curve shows a well-defined peak shape similar to that of the voltammetric peak. Green and Blue color give complementary information for the Prussian Blue ⇄ Everitt’s Salt and Prussian Blue ⇄ Prussian Yellow electrochemical reactions 1-3.

Figure 1. Cyclic voltammograms and derivative color intensities for Prussian Blue films on a Pt electrode in KCl 0.5 M, pH=3.0 solution.

References (1) Agrisuelas, J.; Bueno, P. R.; Ferreira, F. F.; Gabrielli, C.; Garcia-Jareño, J. J.; Gimenez- Romero, D.; Perrot, H.; Vicente, F. Electronic Perspective on the Electrochemistry of Prussian Blue Films. Journal of the Electrochemical Society 2009, 156 (4), P74–P80. (2) Agrisuelas, J.; García-Jareño, J. J.; Vicente, F. Identification of Processes Associated with Different Iron Sites in the Prussian Blue Structure by in Situ Electrochemical, Gravimetric, and Spectroscopic Techniques in the Dc and Ac Regimes. J. Phys. Chem. C 2012, 116 (2), 1935–1947. (3) Agrisuelas, J.; García-Jareño, J. J.; Guillén, E.; Vicente, F. Kinetics of Surface Chemical Reactions from a Digital Video. J. Phys. Chem. C 2020, 124 (3), 2050–2059.

Acknowledgements This work was supported by MINECO-FEDER CTQ2015-71794-R and from Excellence Network E3TECH under project CTQ2017-90659-REDT (MINECO, Spain).

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

SECM and AFM Characterizations for the Study of ORR Catalysts Electrocatalytic Activity at Agglomerate scale

Alice Boudet,a Olivier Henrotte,a Ndrina Limani,a Fatima El Orf,a Frédéric Oswald,a Bruno Jousselme,a and Renaud Cornut a

a Université Paris-Saclay, CEA, CNRS, NIMBE, LICSEN, 91191, Gif-sur-Yvette, France [email protected]

Scanning electrochemical microscopy (SECM) is at the forefront of a new generation of tools enabling to investigate the local properties of catalysts [1]. Thanks to its ability to study a very low amount of material with almost no additives such as a polymeric binder (Nafion), the intrinsic activity of catalysts gets accessible and characterizations can be performed at agglomerate scale. Herein, we propose to combine for the first time SECM with atomic force microscopy (AFM) characterizations to study the link between the catalytic activity and the agglomeration state of non-PGM (platinum group metal) ORR catalysts. SECM is performed with the redox competition mode in acidic media, following the protocol developed recently in our group [2]. AFM images are then used to determine the agglomeration state in the deposits of catalysts.

Different PGM-free ORR catalysts from the European project PEGASUS were investigated at different loadings [3]. Differences in term of dispersion, stability of the inks and adherence on the substrate were observed, which highlights the importance of adapting the ink formulation to each ink. The agglomeration states of the deposits measured by AFM enabled to explain the differences in activity measured by SECM. The performances of the catalysts were compared and the contributions of the intrinsic activity and the agglomeration state were separated. These results illustrate that our approach is suitable for the characterization of catalysts at agglomerate scale, with various applications from the benchmarking of new catalysts to the optimization of an ink formulation.

References

(1) Limani, N.; Boudet, A.; Blanchard, N.; Jousselme, B.; Cornut, R. Local Probe Investigation of Electrocatalytic Activity. Chem. Sci. 2021, 12 (1), 71–98. https://doi.org/10.1039/D0SC04319B. (2) Henrotte, O.; Boudet, A.; Limani, N.; Bergonzo, P.; Zribi, B.; Scorsone, E.; Jousselme, B.; Cornut, R. Steady‐State Electrocatalytic Activity Evaluation with the Redox Competition Mode of Scanning Electrochemical Microscopy: A Gold Probe and a Boron‐ Doped Diamond Substrate. ChemElectroChem 2020, 7 (22), 4633–4640. https://doi.org/10.1002/celc.202001088. (3) Boudet, A.; Henrotte, O.; Limani, N.; El Orf, F.; Oswald, F.; Jousselme, B.; Cornut, R. Unraveling the Link between Catalytic Activity and Agglomeration State with SECM and AFM. in preparation.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Electrochemical Characterization of Shape Memory Steel

C. Mariño, A. Collazo, X.R. Nóvoa, C. Pérez

Universidade de Vigo, E.T.S.E.I., Lagoas-Marcosende, 9 E-36200, Vigo, Spain [email protected]

Keywords: Electrochemical Impedance Spectrocopy (EIS), Shape Memory Steel (SMS), Corrosion, Reinforced Concrete.

A new kind of SMA, with a ferrous base complemented with Mn and Cr additions, the Shape Memory Steel (SMS), is being introduced as a very effective structural reinforcement, that also is more affordable in price than previous options with Ti and Ni bases [1]. This study focuses on the corrosion behavior of the Fe‒17Mn-10Cr‒5Si-4Ni-1(V,C) Shape Memory Steel. The sample is introduced in a 0,1 M NaOH + 0,1 KOH solution (pH = 13) that simulates the alkalinity of the concrete pore solution. A passive layer is formed after 7 days of exposition to the solution, which was corroborated by tracking the potential evolution with time. The stability of this passive layer, and thus, the durability in aggressive environments, is assessed by progressive additions of Cl- ions in the previous solution. The system is studied using the EIS technique and the results are compared with commercial types of carbon steel, commonly used for reinforced concrete. The results suggest that the SMS improves the amount of Cl- that the carbon steel can endure, as Figure 1 shows.

6x104 1 Hz 3 10 mHz 6,0x10 1 Hz 2 1 Hz 4,0x103 . cm

 4 4x10 2,0x103 1 Hz

2,0x103 4,0x103 6,0x103 10 mHz

4 2x10 10 mHz

- Imaginary part / part - Imaginary B500S [0.00 M] B500S [0.15M] SMS [0.00 M] 10 mHz SMS [1.25 M] 0 0 2x104 4x104 6x104 Real Part/ . cm2 Figure 3: Shape Memory Steel (SMS) and carbon steel (B500S) at different chloride concentrations in

a 0,1 M NaOH + 0,1 M KOH solution

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No769255. This document reflects only the views of the authors. Neither the Innovation and Networks Executive Agency (INEA) nor the European Commission is in any way responsible for any use that may be made of the information it contains.

(1) Zhao, C. Shape Memory Stainless Steels, Advanced Materials and Processes, 2001, Volume 159.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Scanning Gel Electrochemical Microscopy (SGECM): the applications and prospects of an emerging electrochemical imaging/patterning technique

Mariela A. Brites Helua, Ning Danga and Liang Liua

aLaboratoire de Chimie Physique et Microbiologie pour les Matériaux et l’Environnement (LCPME), UMR 7564, CNRS-Université de Lorraine, 405 Rue de Vandoeuvre, Villers-lés- Nancy, France. [email protected]

The Scanning Gel Electrochemical Microscopy (SGECM) provides information about the topography and the (electro)chemical activity of samples in air at the same resolution. Unlike classical Scanning Electrochemical Microscopy1 and Scanning Ion Conductance microscopy, SGECM spatially localizes the electrolyte in a gel attached to the electrode-probe (i.e. gel probe). This allows measuring highly reactive/sensitive samples and complex-shaped surfaces. As compared with scanning droplet cell techniques such SECCM, the stability of the gel electrolyte allows to have a better control of the contact between the sample and the probe and to avoid spreading of the solution on the surface. This makes measurements less dependent on the roughness and hydrophobicity of the sample and more reproducible. Moreover, due to the soft nature of the gel, SGECM offers flexible lateral resolution within few tens of microns and can reach up to ca. 1 µm. The home-built instrumentation allows flexible design of experiments beyond those provided by commercial setup. This presentation summarizes the achievements, advantages and prospects of the SGECM. So far, SGECM has well demonstrated its applicability in electrochemical imaging2, potentiostatic studies3, local surface modification4, etc. We offer this emerging tool to the community, seeking for collaborations in any form, especially for broadening the applications of SGECM.

Figure 1. a) Simplified scheme of SGECM setup. b) Gel probe configurations. c) Current mapping of Cu/Al alloy sample d) AgCl spots patterned on Ag plate.

References (1) Scanning Electrochemical Microscopy, 2nd ed.; Bard, A. J., Mirkin, M. V., Eds.; CRC Press: New York, 2012. (2) Liu, L.; Etienne, M.; Walcarius, A. Scanning Gel Electrochemical Microscopy for Topography and Electrochemical Imaging. Anal. Chem. 2018, 90 (15), 8889–8895. (3) Dang, N.; Etienne, M.; Walcarius, A.; Liu, L. Scanning Gel Electrochemical Microscopy (SGECM): The Potentiometric Measurements. Electrochem. commun. 2018, 97, 64–67. (4) Brites Helú, M. A.; Liu, L. Rational Shaping of Hydrogel by Electrodeposition under Fluid Mechanics for Electrochemical Writing on Complex Shaped Surfaces, Chem. Eng. J. 2021, accepted.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Microelectrochemical evaluation of severe localized corrosion sites developing on third-generation aluminium alloys

J. Izquierdo,a,b R.M.P. da Silva,c M.X. Milagre,c I. Costa,c A.M. Betancor-Abreua and R.M. Souto a,b

a Departamento de Química, Universidad de La Laguna, E-38200 La Laguna, Spain b Instituto de Materiales y Nanotecnología, Universidad de La Laguna, E-38200 La Laguna, Spain c Instituto de Pesquisas Energéticas e Nucleares—IPEN, CNEN—Av. Prof. Lineu Prestes, 2242 São Paulo, Brazil [email protected]

Third-generation aluminium-copper-lithium alloys exhibit attractive mechanical properties, in particular light-weight and significant strength. However, the developed microstructure often results in severe localized corrosion (SLC) sites with fast in-depth pit propagation accompanied 1 by H2 evolution. Such phenomena stem from a strong galvanic coupling, mainly established between Fe- and Cu-rich particles and the surrounding matrix. As a result, strong concentration and pH gradients develop throughout the aluminium surface, determining the local breakdown of the passive regime eventually provided by aluminium oxides and corrosion products. Understanding the development of such distributions is key to outline appropriate strategies for the prevention of fast degradation and materials failure.

Scanning Electrochemical Microscopy (SECM) and Scanning Vibrating Electrode Technique (SVET) are capable of providing local information on the distribution of active sites and the presence of reactive chemical species. SVET has previously demonstrated the formation of gas bubbles ascribed to hydrogen evolution (i.e., electro-reduction process) at the anodically- activated sites,2,3; whereas local hydrogen production, oxygen consumption and pH changes are readily accessible using SECM, although with some limitations with regards to the detection of evolving gas.4

The present contribution reports recent advances in the investigation of local degradation phenomena occurring at the surface of Al-Cu-Li alloy AA-2098, as bare material and after friction stir welding. Oxygen consumption over nobler particles acting as cathodic sites, and SLC accompanied with strong acidification and H2 production at the local anodes were observed. The determined pH and concentration gradients allow to progress in the knowledge of the mechanistic aspects involved in the degradation processes on these materials.

References (1) Milagre, M.X.; Donatus, U.; Machado, C.S.C.; Araujo, J.V.S.; da Silva, R.M.P.; de Viveiros, B.V.G.; Astarita, A.; Costa, I. Corrosion Engineering, Science and Technology 2019, 54, 402. (2) He, J.; Tallman, D.E.; Bierwagen, G.P. Journal of The Electrochemical Society 2004, 151, B644. (3) Izquierdo, J.; Fernández-Pérez, B.M.; Santana, J.J.; González, S.; Souto, R.M. Journal of Electroanalytical Chemistry 2014, 732, 74. (4) Thomas, S.; Izquierdo, J.; Birbilis, N.; Souto, R.M. Corrosion 2015, 71, 171.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

EC-SHINERS for Studies of Electrochemical Interfaces

Julia Fernández Vidal a, Thomas A. Gallowaya, Gary A. Attardb and Laurence J. Hardwicka a Stephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK. b Department of Physics, University of Liverpool, UK. [email protected]

The electrocatalytic oxygen reduction reaction (ORR) is the most important cathodic process in fuel cells and metal-air batteries.1,2 The slow reaction kinetics has become a long-recognised challenge, thereby requiring a catalyst to promote the rate of reaction. To date, platinum (Pt) is the most active and stable compound that can catalyse ORR.3 However, after many years of study, the detailed surface mechanism of ORR is still not fully understood, due the inability of the commonly used experimental techniques to detect reaction intermediaries.4 Understanding the basis and fundaments of ORR on Pt surfaces is a necessary step for the design and development of practical and efficient catalysts. The use of single crystals simplifies the study and opens the possibility of correlating specific interfacial properties and the electrochemical processes occurring at the interface.3 Shell-Isolated Nanoparticles for Enhanced Raman Spectroscopy (SHINERS)5 is a powerful technique for surface analysis and its combined use with electrochemistry (EC-SHINERS) provide the opportunity to study and develop a fundamental understanding of the reaction mechanisms at electrochemical interphases. The technique allows the detection of intermediates and products on any electrode surface during an electrochemical reaction, accessing reaction pathways and relating them directly to surface structure.6 The use of SHINERS to study reactions on defined single crystal electrodes is a particular focus and work is presented that continues the study of the ORR focusing on Pt surfaces in non-aqueous solvents.

(1) Dong, J. C.; Zhang, X. G.; Briega-Martos, V.; Jin, X.; Yang, J.; Chen, S.; Yang, Z. L.; Wu, D. Y.; Feliu, J. M.; Williams, C. T.; et al. In Situ Raman Spectroscopic Evidence for Oxygen Reduction Reaction Intermediates at Platinum Single-Crystal Surfaces. Nat. Energy 2019, 4 (1), 60–67. (2) Galloway, T. A.; Hardwick, L. J. Utilizing in Situ Electrochemical SHINERS for Oxygen Reduction Reaction Studies in Aprotic Electrolytes. J. Phys. Chem. Lett. 2016, 7 (11), 2119–2124. (3) Gómez-Marín, A. M. A.; Rizo, R.; Feliu, J. M. Oxygen Reduction Reaction at Pt Single Crystals: A Critical Overview. Catal. Sci. Technol. 2014, 4, 1685. (4) Gómez-Marín, A. M.; Feliu, J. M. New Insights into the Oxygen Reduction Reaction Mechanism on Pt (111): A Detailed Electrochemical Study. ChemSusChem 2013, 6 (6), 1091–1100. (5) Li, J. F.; Huang, Y. F.; Ding, Y.; Yang, Z. L.; Li, S. B.; Zhou, X. S.; Fan, F. R.; Zhang, W.; Zhou, Z. Y.; Wu, D. Y.; et al. Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy. Nature 2010, 464 (7287), 392–395. (6) Galloway, T. A.; Dong, J.-C.; Li, J.-F.; Attard, G.; Hardwick, L. J. Oxygen Reactions on Pt{hkl} in a Non-Aqueous Na+ Electrolyte: Site Selective Stabilisation of a Sodium Peroxy Species. Chem. Sci. 2019, 10, 2956–2964.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Electrochemical and surface characterization of Mn-phosphate conversion layers developed on high strength steel

B. Díaz, Y. Beltrán, X. R. Nóvoa, C. Pérez, and S. Silva

Encomat Group, University of Vigo, Campus As Lagoas-Marcosende, 36310 Vigo, Spain [email protected]

Manganese phosphate layers are widely used due to their suitable corrosion resistance and to their lubricant ability, being particularly valuable in the cold working processes such as wire or deep drawing. The coating formation process is based in a conversion reaction where the metal surface is chemically modified until achieving a uniform and firmly adhered layer. The dipping process is generally used, and thus, the phosphate coatings were developed by immersion of the prior pickled specimens in a bath containing phosphoric acid along with a Mn salt (MnCO3).

Several modifications of the phosphating bath conditions have been considered in this study. The effect of the ultrasonic vibration, induced during the deposition process, was checked along with the immersion time [1]. Whereas the deposition times does not appear to have a great influence on the appearance and thickness of the layer, the ultrasonic agitation promotes the development of a finer-grained structure.

The addition of several accelerating agents into the phosphating bath was also studied, in particular, Ni(NO3)2, Ce(NO3)3 and SDS (Sodium Dodecyl Sulfate) were tested. The amount of the three chemicals was varied from 2 g/L to 16 g/L. The combination of the suitable amount of the accelerating along with the ultrasonic vibration promotes the development of the most effective coating in terms of compactness.

The surface analysis was completed using the SEM, and thus, information concerning the coating appearance and its chemical composition can be provided. For the electrochemical characterization, the impedance spectroscopy and the linear sweep polarization techniques were used. The analysis of the corrosion rate given by the two methods allowed gathering information about the covering efficiency, that is, the coating porosity [2].

References (1) Díaz, B.; Freire, L.; Mojío, M.; Nóvoa, X. R. Journal of Electroanalytical Chemistry 2015, 737, 174. (2) de Freitas Cunha Lins, V.; de Andrade Reis, G. F.; de Araujo, C. R.; Matencio, T. Applied Surface Science 2016, 253, 2875.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Supporting Pt(Cu) Nanoparticles on Mesoporous Carbons for PEMFC

Julia Garcia-Cardona, Ignasi Sirés, Francisco Alcaide, Enric Brillas and Pere L. Cabot

Laboratori d’Electroquímica dels Materials i del Medi Ambient, Secció de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain [email protected]

Main drawbacks when using Pt as catalyst in the anode of polymer electrolyte membrane fuel cells (PEMFCs) are that it is easily poisoned by CO and its cost. The strategy of air-bleeding has shown to increase the CO tolerance in PEMFC,1 but still limited to few ppm of CO. Other strategies are the use of PtRu alloys, which are still expensive, and the synthesis of nanoparticles with a sacrificial metal core and a Pt shell. The latter may allow reducing the amount of Pt used in the electrode and thus the catalyst cost and also increasing its tolerance towards CO because of the electronic effect of the transition metal on Pt.2 A further step would be to improve the carbon support to increase stability. The current carbon blacks present poisonous impurities and micropores that can trap the catalyst nanoparticles, and show thermochemical instability.3 Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have been tested as supports for Pt(Cu) nanoparticles with promising results.4 Therefore, in this work, Pt(Cu) nanoparticles have been synthesized either on commercial ordered mesoporous carbons (OMCs) like CMK-3 and CMK-8, or purpose-made micro/mesoporous carbons. All these supports present improved textural and electrochemical properties as compared to carbon blacks.3 As an example, Figure 1 shows lower onset potentials for CO oxidation in the case of commercial OMCs. 4.0

-2 3.0 CMK3 2.0 cm CMK3A ꞏ 1.0 CMK8 0.0 CMK8A / mA / mA

-1.0 j -2.0 Pt/C -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 E / V

-1 Figure 1. CO stripping curves in deaerated 0.50 M H2SO4 solution at scan rate of 20 mV s .

References (1) A. Velázquez-Palenzuela, E. Brillas, C. Arias, F. Centellas, J.A. Garrido, R.M. Rodríguez, P.L. Cabot, J. Catal. 2013, 298, 112–121. (2) G. Caballero-Manrique, A. Velázquez-Palenzuela, E. Brillas, F. Centellas, J.A. Garrido, R.M. Rodríguez, P.L. Cabot, Int. J. Hydrogen Energy 2014, 39, 12859–12869. (3) S. Sharma, B.G. Pollet, J. Power Sources 2012, 208, 96–119. (4) J. Garcia-Cardona, I. Sires, F. Alcaide, E. Brillas, F. Centellas, P.L. Cabot. Int. J. Hydrogen Energy 2020, 45, 20582-20593

Acknowledgements Financial support from PID2019-109291RB-I00 (AEI, Spain) and the PhD scholarship received by J.G.C. (2020 FISDU 00005, Generalitat de Catalunya) are acknowledged.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Surface reactivity and chemical evolution of corrosion-inhibited copper by means of Scanning Electrochemical Microscopy

B. Hernández-Concepción,a J. Izquierdo,a,b and R.M. Soutoa,b

a Departamento de Química, Universidad de La Laguna, E-38200 La Laguna, Spain b Instituto de Materiales y Nanotecnología, Universidad de La Laguna, E-38200 La Laguna, Spain [email protected]

Different features resulting from the protection provided by organic corrosion inhibitors on metals can be addressed by using Scanning Electrochemical Microscopy (SECM), thereby revealing the alterations of the surface conductivity following adsorption of the inhibitor as well as the nature of the chemical environment. The so-called feedback mode of SECM, sensitive to the capability of the surface to locally regenerate a given redox mediator previously converted at the probe sensor, can provide quantitative information on the heterogeneous blockage of the available active sites.1 Meanwhile, the chemical sensitivity of (ultra)microelectrodes towards electrochemically-active species may also report on the generation of metal cations, resulting from corrosion phenomena, next collected at the probe.2,3 Hence, both modes may provide complementary information regarding the decrease of degradation rate (i.e., metal dissolution) and alteration of the surface properties (e.g., inhibition of any electrochemical conversion and/or passivation). Nevertheless, their complementarity is limited to the implementation in different experimental conditions, namely potential applied to the microelectrode and electrolyte.

Both, generation-collection and feedback SECM modes, are typically conducted under potentiostatic conditions, although the former may require an additional step involving anodic stripping and redissolution if the metal cations of interest can only be electrochemically sensed by its reduction to metallic state at the probe, as it happens with Cu2+.3 Hence, potentiodynamic methods, concomitantly involving local sensing and redissolution, are attractive to map the chemical environment, becoming key for simultaneous imaging of the surface properties with the assistance of added electro-active species (e.g., redox mediators). The application of variable tip potential during the scan may hence provide valuable information on different features (quasi)simultaneously. This contribution explores the use of potentiodynamic methods in SECM with the scope of advancing in the simultaneous analysis of copper corrosion inhibition and the heterogeneous evolution of the surface conductivity.

References (1) Varvara, S.; Caniglia, G.; Izquierdo, J.; Bostan, R; Găină, L.; Bobis, O.; Souto, R.M. Corrosion Science 2020, 165, 108381. (2) Souto, R.M.; González-García, Y.; González, S.; Corrosion Science 2005, 47, 3312. (3) Izquierdo, J.; Eifert, A.; Kranz, C. Souto, R.M.; Electrochimica Acta 2017, 247, 588.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Engineered unique structure of Pd-Fe for high thresholds of electrocatalytic performance in oxygen reduction and glycerol oxidation reactions

Yaovi Holade,a Hazar Guesmi,b Sophie Tingry,a and David Cornua a IEM, UMR 5635, Univ Montpellier, ENSCM, CNRS, 34090 Montpellier, France b ICGM, UMR 5253, Univ Montpellier, ENSCM, CNRS, 34090 Montpellier, France [email protected]

One of the unsolved important fundamental and applied questions in heterogeneous electrocatalysis for energy conversion/storage is about our ability to engineer a unique electrocatalyst that can simultaneously operate for both anode (fuel oxidation) and cathode (O2 reduction, ORR) without changing the composition/structure or the synthesis method. Our present contribution accounts for a solution in the case of iron-diluted Pd nanoparticles (Figure 1).1 ORR is the common bottleneck of the pollution-free electricity production with alkaline technologies of rechargeable metal-air batteries and fuel cells. As alternative to scarcely Pt, Pdbased materials have attracted much attention for different applications in heterogeneous catalysis and not only for ORR, but also for glycerol (biomass-based byproduct) oxidation that is also common reaction (anode) for fuel cells and low-energy input electrolyzers to produce green H2. So, being able to prepare a nanocatalyst that is simultaneously active and durable for both ORR and glycerol oxidation is highly desired. Figure 1 highlights that the support plays an important role and the presence of Fe (20%) dramatically improves the performance. The developed bimetallic PdFe performed efficiently and selectively ORR in alkaline media at the maximum faradaic yield of four-electron transfer (100%) and high kinetic current density jk of −2 −1 2 mA cm Pd (1 A mg Pd) at 0.9 VRHE, which largely exceeds the tested commercial Pd/C and the literature. For glycerol electrooxidation, the obtained peak current density of jp = 2.3 mA −2 −1 cm Pd (1.1 A mg Pd) and faradaic efficiency of FE = 83-99% outperformed the commercial −2 −1 Pd/C (jp = 0.47 mA cm Pd (0.39 A mg Pd, FE = 78%) and the majority of the reported catalysts. Our conducted DFT calculations reveal that the high performance of the bimetallic PdFe arises from a unique structure with Pd in the core plus skin and Fe in the second layer. This particular configuration of skin surfaces has been reported2 for PtNi to trigger high electrocatalytic kinetics for ORR. Those findings open new possibilities in the development of multifunctional nanocatalysts for the sustainable electrochemical energy conversion and storage. Figure 1. Left: Tafel plots of the kinetic current density from ORR before and after the accelerated ageing of 10,000 cycles (O2- saturated 0.1 M KOH, 1600 rpm, 0.005 V s−1). Center: Synthesized structure (by STEM-EDX overlay), and calculated structure (by DFT) of PdFe. Right: Voltammograms of electrocatalytic glycerol glycerol, oxidation 0 rpm, 0.05(1 V s M KOH, 0.1 −1). References (1) Manuscript under review. (2) Stamenkovic, V. R.; Fowler, B.; Mun, B. S.; Wang, G.; Ross, P. N.; Lucas, C. A.; Marković, N. M. Science 2007, 315 (5811), 493-497.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Reactive Electro-Mixing Reactor: Comparison with Static Electrochemical Devices

Emmanuel Mousseta

a Laboratoire Réactions et Génie des Procédés, Université de Lorraine, CNRS, LRGP, F- 54000 Nancy, France [email protected]

Since the first battery proposed in 1799 by Alessandro Volta, the vision of the electrochemical reactor design did not drastically change. The electrolyte is stirred or pumped between/through static or semi-static (rotating disk or cylinder devices) cells. Here, it is proposed for the first time to implement electrochemical cells as blade of impeller (namely “electro-blade”), while the liquid is stirred by the electrodes in motion [1]. This “reactive electro-mixing” (REMix) reactor make the use of perforated boron-doped diamond (BDD) anode and porous carbon felt (CF) cathode with micrometric inter-electrodes distance (500 µm) (Figure 1a). The degradation efficiency of paracetamol as representative pharmaceutical pollutant in low-conductivity media ( 1 mS/cm) is compared with two other configurations: (1) static electrodes in REMix reactor, while the solution is stirred by a magnetic bar, (2) conventional filter-press cell using microfluidic thin film device [2]. The results highlight the 25% increase of degradation kinetics with REMix device as compared to static micro-reactor, while the absence of magnetic stirring limit notoriously the performance (Figure 1b). Moreover, the synergy obtained with the REMix apparatus permit to decrease 20-times the energy consumption compared with conventional static system, which ensure promising research for the development of reactive electro-mixing.

Figure 1. (a) Novel REMix reactor involving two electrochemical cells in rotation; (b) comparison of REMix performance with conventional static micro-reactor.

References [1] Mousset, E. Electrochemistry Communications 2020, 118, 106787. [2] Mousset, E.; Puce, M; Pons, M.N. ChemElectroChem 2019, 6, 2908–2916.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Metal carbides for the electrochemical hydrogen evolution reaction

Sergio Coello, Yapci Remedios-Díaz, Carmen Arévalo, Gonzalo García, Elena Pastor

Instituto de Materiales y Nanotecnología, Departamento de Química, Universidad de La Laguna, PO Box 456, 38200, La Laguna, Tenerife, España [email protected]

The development of catalysts without noble metals with high activity for reactions in water electrolyzers appears as the best option to reduce the cost of the production of high purity H2. Transition metal carbides (TMCs) emerge as an alternative to platinum for this application [1]. On the other hand, ionic liquids (ILs) have generated interest in electrochemical applications due to their electrical and mechanical properties [2].

In this work, composite materials have been prepared with TMCs and octylpyridinium hexafluorophosphate (OPy), carrying out their physicochemical characterization by electron microscopy and Raman spectroscopy, among others. The activity towards the hydrogen evolution reaction (HER) has been studied by means of differential electrochemical mass spectrometry (DEMS) following the ionic current for m/z = 2 to calculate the Tafel slopes. This new method to find the rate determining step allows to discriminate contributions to the reduction currents other than the that for hydrogen production (e.g., surface oxide reduction currents), being able to obtain more precise Tafel slopes [3]. Screen-printed electrodes (SPEs) have been used to perform rapid tests in the detection of the electrocatalytic properties of composite materials, obtaining results that are comparable with those obtained in a conventional cell, but in a simpler and cheaper way.

The results show that the presence of OPy in the mixture affects the particle sizes and vibrations detected by Raman spectroscopy (mainly oxides). This produces differences in the electrocatalytic activities of the materials, displacing the HER overpotential.

It is concluded that IL modifies the stability of surface oxides, decreasing for TMCs of group VI (W and Mo) but increasing for VC and TiC. This change in the stability of the oxides could be the cause of the differences in catalytic activity and particle sizes.

Acknowledgements This work has been supported by the Spanish Ministry of Science (MICINN) under project ENE2017-83976-C2-2-R (co-founded FEDER). S.D-C. thanks the ACIISI for his Ph.D. fellowship and G.G. acknowledges the “Viera y Clavijo” program (ACIISI & ULL).

Referencias [1] Liu, Y.; Kelly, T.G.; Chen, J.G.; Mustain, W.E. ACS Catal. 2013, 3, 1184-1194. [2] Appetecchi, G.B.; Kim, G.T.; Montanino, M.; Alessandrini, F.; Passerini, S. J. Power Sources 2011, 196, 6703-6709 Flórez-Montaño, J.; García, G.; Guillén-Villafuerte, O.; Rodríguez, J.L.; Planes, G.A.; Pastor, E. Electrochim. Acta, 2016, 209, 121–31. [3] Díaz-Coello, S. García, G.; Arévalo, M.C.; Pastor, E. Int. J. Hydrogen Energy, 2019, 44, 12576-12582.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Microbial Desalination Cells using air diffusion and liquid cathode reactions: study of the salt removal and desalination efficiency

Marina Ramírez-Moreno1, Pau Rodenas1, Martí Aliaguilla2, Pau Bosch-Jimenez2, Eduard Borras2, Patricia Zamora3, Víctor Monsalvo3, Frank Rogalla3, Juan M. Ortiz 1, Abraham Esteve- Núñez1,4 1IMDEA Water Institute, Avenida Punto Com, 2, Parque Científico Tecnológico de la Universidad de Alcalá, 28805, Alcalá de Henares, Madrid, Spain. 2LEITAT Technological Center, C/Pallars, 179-185, 08005 Barcelona, Spain. 3FCC Aqualia S.A., Avenida del Camino de Santiago, 40, Building 3, 4th floor, 28050, Madrid, Spain. 4Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering Department, Universidad de Alcalá, Alcalá de Henares, Spain. [email protected]

Microbial Desalination Cell (MDC) represents an innovative technology which accomplishes simultaneous desalination and wastewater treatment without external energy input. MDC technology could be employed to provide freshwater with low-energy input, for example, in remote areas where organic wastes (i.e. urban or industrial) are available. This study compares the desalination performance of two laboratory-scale MDCs located in two different locations for brackish water and sea water using two different strategies [1]. The first strategy consisted of an air cathode for efficient oxygen reduction, while the second strategy was based on a liquid catholyte with Fe3+/Fe2+ solution (i.e. ferro-ferricyanide complex). Pros and cons of both strategies are discussed for subsequent upscaling of MDC technology.

Figure 1. Diagram of an MDC unit. AEM/CEM: anion/cation exchange membrane.

ANKNOWLEDGEMENTS Project “MIDES – H2020” has received funding from the European Union’s Horizon 2020 research and innovation programme (Nº 685793). Juan M. Ortiz acknowledges the financial support of Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (Proyecto BioDES, CTM2015-74695-JIN). Support from the E3TECH Excellence Network under project CTQ2017-90659-REDT (MCIUN, Spain) is also acknowledged. References 1. Ramírez-Moreno, M. et al. , Comparative Performance of Microbial Desalination Cells Using Air Diffusion and Liquid Cathode Reactions: Study of the Salt Removal and Desalination Efficiency, Front. Energy Res. 7 (2019) 135. doi: 10.3389/fenrg.2019.00135

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Microfluidics Applied to Redox Flow Batteries: A Membraneless Breakthrough Technology

B. Oraáa,b, A. Bernaldoa, B. Ruiza, J. Palmab, A. E. Quinteroa

a Micro Electrochemical Technologies S.L., Móstoles Tecnológico, C/ Federico Cantero Villamil, 2B, 28935 Móstoles, Madrid, Spain b IMDEA Energy Institute. Av. Ramon de la Sagra 3, 28935 Móstoles, Madrid, Spain [email protected]

Redox Flow Batteries (RFB) are a promising candidate for the transition from fossil fuels to renewable energies because they can remedy the intermittency problem of so called “green energies”, as wind and solar. RFBs can provide long durability and low manufacturing and operating costs. Additionally, they can decouple generated power from the amount of stored energy, thus facilitating a cost effective scalability (1). Moreover, RFBs usually do not undergo a phase change, which allows to reach large number of charge/discharge cycles (2). As drawback, most flow batteries require an ion-selective membrane to keep reagents separated while maintaining the necessary ion flow to complete the circuit. These membranes can limit the durability, increase production cost and limit the maximum current intensity. The recent advance in microfluidics field provides a possibility to eliminate the use of membranes in flow batteries. In the microscale, fluid mechanics is characterized by low Reynolds numbers which is indicative of laminar flows. This allows to remove the membrane, reducing cell internal resistance and decreasing production cost. Other advantages that microscale can provide are the increase in gradients due to lengths decrease, greater surface- volume ratio and greater speed to reach thermal and chemical equilibrium of the reaction (3). This concept poses new challenges, such as special cell designs and accurate flow control to avoid electrolytes mixing, and electrodes improvement for the reaction to proceed achieving high redox conversion, but avoiding mixing of species by diffusion. A membrane-less micro flow battery prototype with Vanadium electrolyte is presented here. This system operates with a piezoelectric pumping system and flow rate sensors in order to control fluid streams. Cell reaction chamber has been manufactured by 3D micro-printing technology based on original designs. This is the first operative micro flow battery that demonstrates multiple charge- discharge cycles. Optimization of the performance, based on voltage, capacity and efficiencies of lab-scale prototypes, has been carried out modifying operating conditions such us flow rate, temperature and current densities.

References (1) Weber, A. Z., Mench, M. M., Meyers, J. P., Ross, P. N., Gostick, J. T., & Liu, Q. Journal of Applied Electrochemistry, Redox flow batteries: a review, 2011, 41(10), 1137. (2) Goulet, M. A., & Kjeang, E. Journal of Power Sources, Colaminar flow cells for electrochemical energy conversion, 2014, 260, 186196. (3) Modestino, M. A., Rivas, D. F., Hashemi, S. M. H., Gardeniers, J. G. E., & Psaltis, D. Energy & environmental science, The potential for microfluidics in electrochemical energy systems, 2016, 9(11), 33813391.

Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Water Desalination by Capacitive Deionization Using Graphite Felt 3D Framework Composites

Julio J. Ladoa, Yang Wanga,b,c#, Inés Vázquez-Rodrígueza, Cleis Santosd, Enrique García- Quismondoa, Jesús Palmaa, Marc A. Andersona,

a Electrochemical Processes Unit, IMDEA Energy, Ave. Ramón de la Sagra 3, E28935, Mostoles, Madrid, Spain b School of Chemical Engineering and Technology, Tianjin University, No. 135 Yaguan Road, Tianjin, China c Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin 300072, PR China d IMDEA Materials Institute, Tecnogetafe. Eric Kandel, 2, 28906, Getafe, Madrid, Spain [email protected]

Capacitive Deionization (CDI) is an emerging technology for brackish water desalination. Currently, CDI technology lacks practical means of scaling electrodes from the laboratory to pilot plant level for pre-commercial applications. With the aim of solving the scalability issues, we have prepared easy to scale 3D composites using the highly conductive macrostructure of a graphite felt (GF) as electron transfer channel with the microstructure of activated carbon (AC) to furnish ionic adsorption sites (GF-AC). The electrochemical characterization of GF-AC showed a larger total ion storage capacity as compared to an AC film electrode prepared with the same active material. GF-AC was then tested in a 1-Cell CDI System (10 cm2) reaching salt adsorption capacity (SAC) values of 5.2-8.7 mg g-1, 57-67% in charge efficiency and stable long-term operation (30% loss after 120 cycles). Finally, the system was scaled to a 9-Cell Stack (300 cm2) and tested using different operational modes (batch and single pass), parameters (flow, current density and voltage limit) and electrolyte concentrations (7 mM, 20 mM and 37 mM). Results in terms of productivity (2–47 L h-1 m2) and energy consumption (0.1-0.7 kWh m-3) associated to salt concentration reductions (0.5- 10.0 mM) evidenced the versatility of CDI technology.

Fig. 1. GF-AC electrode was scaled from a Swagelok® cell to a 9-cell CDI system (300 cm2 electrodes).

Financial support from Excellence Network E3TECH under project CTQ2017-90659-REDT (MINECO, Spain) is acknowledged.

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Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Hierarchical Graphene supports to increase nanosized Nickel-based catalyst efficiency for water splitting

González-Ingelmo, M.; Blanco, C., Santamaría, R., Álvarez, P., Granda, M., Rocha,V.G. Instituto de Ciencia y Tecnología del Carbono-INCAR, CSIC, 33011-Oviedo, España. [email protected]

The massive use of traditional fossil fuels has caused serious problems of environmental issues and climate change. In this scenario, the development of clean and renewable energy systems is mandatory to progress towards a more sustainable society. In this regard, water splitting is a key reaction for the clean production of sustainable fuel that consists of two half reactions, namely, oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), being OER the bottleneck of this process. The state-of-the-art electrocatalysts for this reaction are based on noble metals (Ru or Ir complexes) [2]. However, high cost and scarcity of precious electrocatalysts seriously prohibit the large-scale application. Thus, it is essential to explore low-cost, earth-abundant, environmentally friendly, efficient, and stable materials (e.g., Ni, Co, Fe, Cu and Mo). In particular, Ni-based composites are potential substitutes of noble metals for its abundance and electrochemical efficiency [3]. A major challenge for the development of these catalysts when carbon materials are used as supports is achieving a homogeneous distribution and particle size control, especially for optimizing their electrical conductivity, catalytic performance and maximize their durability. Graphene oxide freeze casting processing is a powerful technique to overcome these challenges. According to these premises, water-based NiO precursors such as nitrates and lactates were combined with different flake size graphene oxides to freeze cast hierarchical porous structures. After thermal reduction, the hierarchically Ni-based/graphene casted were characterized by XPS, ICP, SEM, HRTEM and SAED. SEM and HRTEM images show porous (5-30µm) structures homogeneously decorated with nanosized nickel-based particles (Figure 1). The synthetized electrocatalysts were dispersed in IPA/H2O with 0.02 wt.% Nafion and drop-casted on to a graphite disc to form a thin film (0.1 mg/cm2) and study their electrocatalytic behavior. Conditioning and activation cycles via cyclic voltammetry before the linear sweep voltammetry (1.2-1.8 V vs RHE, 1mVs-1) experiments were performed in a Teflon home-made three-electrode cell at room temperature and under inert atmosphere and 1M KOH electrolyte. The different Ni-based/graphene synthetized require overpotential values between 387-457 mV to reach 10 mA cm-2 showing an iR-corrected Tafel -1 slope of 50.6 ± 4.3 mV dec . These results are comparable to that of IrO2 nanoparticles in the same cell and conditions (overpotential of 406 mV and a Tafel slope of 50.9 mV dec-1), indicating superior activity of our Ni-based electrocatalysts.

Figure 1.SEM (Left) and HRTEM (Right) images of Ni-based/graphene freeze casted foam References: [1] Hou J., Advanced Functional Materials, 2019, 29, 1808367. [2] Sánchez-Page B., Journal of Organometallic Chemistry, 2020, 919,121334. [3] Li Y., ChemCatChem, 2019, 11, 5913-5928. Acknowledgements: Funding bodies AEI/PID2019-104028RB-100 and RYC2018-024404-I

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Electrochemical Behavior of Dopamine on Glassy Carbon and Gold Electrodes. A Comparative Study Based on Catechol to Produce Polydopamine by Electrochemical Polymerization

Guadalupe Sánchez, Yolanda Oliva, Rafael Madueño, José M. Sevilla, Manuel Blázquez, Teresa Pineda

Departamento de Química Física y T.A., Universidad de Córdoba, Spain, Instituto Universitario de Nanoquímica (IUNAN), Universidad de Córdoba, Spain [email protected]

Cyclic voltammetry has been applied to the study of the oxidation pathways of catecholamines in vivo allowing positive identification of the transient intermediates, i.e, the open-chain o- quinones, and determinations of the rate of intramolecular cyclization to the substituted indole and its subsequent oxidation to amine chrome [1]. The effect of following chemical reaction during chronoamperometry and cyclic voltammetry at microelectrodes as evaluated by digital simulation, has demonstrated the utility of microelectrodes to monitor catecholamine secretion from individual biological cells. Diffusion coefficients of catecholamine neurotransmitters, their metabolites and related species were measured on brain extracellular fluid using in vivo voltammetric techniques.

Kinetics studies on electrochemical oxidation of catechol in the presence of cycloheptylamine and aniline show that the addition reaction of the quinone with primary amines allows calculate homogeneous rate constant based on experimental and digital simulations.

Moreover, self-polymerization of dopamine has become a promising method to form thin polymer film through a simple deposition process with control over film thickness and removal of templates [2]. Therefore polydopamine is currently considered an efficient and robust platform to functionalize different substrate for high performance polymer composites. However, the mechanism to control the film composition is not well known [3].

In the present work we explore the electrochemical oxidation of dopamine to understand the initial and main steps in the electrochemical polymerization reaction under different experimental conditions to control composition, thickness, and surface functionalization.

References 1. Hawley, M.D.; Tatawawadi, S.V.; Piekarski, S.; Adams, R.N., J. Am. Chem. Soc., 1967, 89, 447-450 2. Wang, J.; Li, B.; Li, Z.; Ren, K.; , Jin L.; Zhang, S.; Chang, H.; Sun, Y.; Jian Ji, J., Biomaterials 2014, 35, 7679-7689 3. Almeida, L.; Correia, R.; Marta, A.; Squillaci, G.; Morana, A.; Cara, F.; Correia, J.; Viana, A., Applied Surface Science 2019, 480, 979–989

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Development of a thin layer bidimensional spectroelectrochemistry cell with easy control of the thickness.

Martin Perez-Estebanez1, Juan V. Perales-Rondon1,2, Sheila Hernández1, Aranzazu Heras1, Alvaro Colina1 1.- Universidad de Burgos, Department of Chemistry, Plaza Misael Bañuelos s/n, E-09001, Burgos, Spain 2.- Universidad de Alcalá de Henares, Department of Chemistry, Alcalá de Henares, Spain. [email protected]

For many years, spectroelectrochemistry (SEC) in thin-layer configuration has been widely used, since the interpretation of the results is quite simple1,2. Particularly, inorganic chemists adopted this configuration to obtain the spectra of inorganic compounds in different redox states, the number of electrons involved in the electrode reaction and the formal potential of the redox couples. Moreover, the first commercialized cell for SEC was a thin layer electrochemical cell using gold grid optically transparent electrodes (OTE). However, SEC in thin-layer configuration also have some drawbacks. Usually, this configuration shows a huge ohmic drop, due to the large distance between the reference and the auxiliary electrode from the working electrode embedded in the thin-layer. Additionally, controlling the thickness of the layer can be a difficult task. In a previous work3 of our group, a simple thin-layer SEC cell in parallel arrangement was developed. In that case, the diffusion layer was limited by the optical fibers diameter, limiting the thickness of the cells to the optical fibers available in the market. Moreover, optical fibers are covered by a cladding material and, therefore, the micrometers of solution closest to the electrode surface cannot be ever observed. In this work, a new experimental setup for thin-layer bidimensional SEC has been developed. The new device allows us to control the thickness of the solution between the working electrode and an inert wall with micrometric precision using piezoelectric positioners, making possible to change the thickness of the cell even during the electrochemical experiment. This approach allowed us sampling the closest solution to the electrode, avoiding the problem of the cladding material of the optical fibers. In our design, reference and auxiliary electrode are placed very close to the thin-layer, minimizing the ohmic drop. The new setup is very useful and versatile, offering several advantages respect to other cell designs for this purpose.

ACKNOWLEDGMENTS Authors acknowledge the financial support from Ministerio de Economía y Competitividad (Grants CTQ2017-83935-R-AEI/FEDER, UE), Ministerio de Ciencia, Innovación y Universidades (RED2018-102412-T) and Junta de Castilla y León (Grant BU297P18). F.O. thanks its contract funded by Junta de Castilla y León, the European Social Fund and the Youth Employment Initiative. S.H. thanks its contract funded by Junta de Castilla y León.

REFERENCES (1) Garoz‐Ruiz, J.; Perales‐Rondon, J. V.; Heras, A.; Colina, A. Electroanalysis 2019, 31 (7), 1254. (2) Garoz‐Ruiz, J.; Perales‐Rondon, J. V.; Heras, A.; Colina, A. Isr. J. Chem. 2019, 59 (8), 679. (3) Garoz-Ruiz, J.; Guillen-Posteguillo, C.; Heras, A.; Colina, A. Electrochem. Commun. 2018, 86, 12.

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Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Friday July 09th, 2021

8h00 - 8h15 Opening Workshop 8h15 - 9h00 Plenary Lecture : Jean-Pierre Sauvage (chair: Hubert Perrot)

9h00 - 10h15 Session 1

Room 24 (chair:Elena Pastor) Room 34A (chair:Iluminada Gallardo) Maria Escudero Escribano Angel Cuesta Frederic Maillard Laurent Bouffier Jose Solla Gullon Eduardo Laborda

10h15 - 10h45 Coffee break 10h45 - 12h00 Session 2

Room 24 (chair:Corinne Lagrost) Room 34A (chair:Christophe Leger) Marian Chatenet Frederic Lemaitre Francisco J. Recio Manon Guille-Collignon Nuria Garcia Araez Vincent Noel

12h00 - 13h30 Lunch 13h30 – 14h Flash Poster Session

Room 24 (chair:Beatriz Puga) Room 34A (chair:Maria Gomez Mingot) Elli Vichou Selma Bencherif Christine Ranjan Maxime Pontie Getaneh Dires Gesesse Theophile Gaudin

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14h00 - 15h15 Session 3

Room 24 (chair:Jalal Ghilane) Room 34A (chair: Joaquin Gonzalez) Christophe Bucher Ivan T. Lucas Yann Leroux Daniel Martin Yerga Christelle Gautier Gonzalo Guirado

15h15 - 15h45 Coffee break 15h45 - 17h Session 4 Room 24 (chair: J.M. Ortiz) Room 34A (chair:Ramon Novoa) Cristina Saez Fabien Miomandre Ignacio Sires Sadornil Alvaro Colina Sergi Garcia Segura Mathieu Etienne

17h - 17h30 Closing Ceremony

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From Solar Energy Research to Molecular Machines and Motors

Jean-Pierre Sauvage

Institut de Science et d'Ingénierie Supramoléculaires University of Strasbourg, F-67000 Strasbourg, France [email protected]

Spitting the water molecule to H2 and ½ O2 represents a very attractive approach for converting light (solar) energy to chemical energy. The most popular transition metal complex in this 2+ research field used to be [Ru(bipy)3] (bipy : 2,2'-bipyridine). In the 80s, one of the research projects of our group was to replace the ruthenium(II) complex by a more accessible first raw transition metal complex. Indeed, copper(I) complexes containing two intertwined ligands 2+ display photochemical properties which are very similar to those of [Ru(bipy)3] . Such copper(I) complexes have thus been made and studied in relation to photochemical water splitting. Inspired by the structure of these complexes, we decided to jump into a new field and to use our knowledge of copper(I) chemistry for preparing catenanes (interlocking ring compounds) in a very simple way. The simplest catenane, a [2]catenane, consists of two interlocking rings. Rotaxanes consist of rings threaded by acyclic fragments (axes). Interlocking ring compounds have attracted much interest in the molecular sciences, first as pure synthetic challenges and, more recently, as components of functional materials. In particular, these compounds appear as perfect precursors to dynamic systems for which motions can be triggered and controlled in a precise manner. This property led to the use of catenanes and rotaxanes as molecular machine prototypes. Subsequently, the research field of artificial molecular machines has experienced a spectacular development, in relation to molecular devices at the nanometric level or mimics of biological motors. In biology, motor proteins are of the utmost importance in a large variety of processes essential to life (ATPase, a rotary motor, or the myosin-actin complex of striated muscles behaving as a linear motor responsible for contraction or elongation). A few recent systems are based on simple or more complex rotaxanes or catenanes acting as switchable systems or molecular machines. Particularly significant examples include a "swinging catenane", "molecular shuttles" as well as multi-rotaxanes reminiscent of muscles or able to act as molecular compressors or switchable receptors. The molecules are set in motion using electrochemical, photonic or chemical signals. Examples will be given which cover the various approaches used for triggering the molecular motions implied in various synthetic molecular machine prototypes. The work of various groups using non interlocking compounds will also be briefly discussed. Potential applications of rotaxanes and molecular machines will also be mentioned.

Sauvage, J.-P. Angew. Chem. Int. Ed., 2017, 56, 11080.

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Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Structure sensitivity and electrolyte effects on oxygen and carbon monoxide electrocatalysis

María Escudero-Escribano Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark [email protected]

Understanding the structure of the electrochemical interface and the structure-reactivity relationships is essential to design and develop more active and selective electrocatalysts. This talk will focus on recent strategies to elucidate and tailor the interfacial structure and properties of electrochemical interfaces and novel electrocatalyst materials for renewable energy conversion reactions. We have recently developed self-supported high surface area nanostructured Ir-based and Pt- based networks for oxygen evolution and reduction reactions (OER and ORR), respectively [1,2]. These networks show a unique morphology and combine excellent mass activity with promising stability. We have studied the role of anions from the electrolyte on Ir nanoparticles for OER; both the composition and concentration of the acidic electrolyte play an important role on the OER performance of Ir nanoparticles [3]. We have also investigated Cu single- crystalline electrodes in contact with different electrolytes to understand the structure sensitivity and electrolyte effects for the electrochemical reduction of CO2 and CO [4-6]. We show how model studies on well-defined surfaces are essential to understand the interfacial structure- property relationships and design efficient electrocatalysts for energy conversion.

REFERENCES

[1] A.W. Jensen, G.W. Sievers, K.D. Jensen, J. Quinson, J.A. Arminio-Ravelo, V. Brüser, M. Arenz, M. Escudero-Escribano, Journal of Materials Chemistry A 2020, 8, 1066. [2] G.W. Sievers et al., Nature Materials 2021, 20, 208. [3] J.A. Arminio-Ravelo, A.W. Jensen, K.D. Jensen, J. Quinson, M. Escudero-Escribano, ChemPhysChem 2019, 20, 2956. [4] P. Sebastián-Pascual, S. Mezzavilla, I.E.L. Stephens, M. Escudero-Escribano, ChemCatChem 2019, 21, 2626. [5] P. Sebastián-Pascual, M. Escudero-Escribano, ACS Energy Letters 2020, 5, 130. [6] P. Sebastián-Pascual, A.S. Petersen, A. Bagger, J. Rossmeisl, M. Escudero-Escribano, ACS Catalysis 2021, 11, 1128.

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The potential profile across the electrode-electrolyte interface: cation size effects and implications for CO2 electrocatalysis Ghulam Hussain, Onagie Ayemoba, Laura Pérez-Martínez, Marco Papasizza, Gema Cabello Jiabo Le, Jun Cheng and Angel Cuesta Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen AB24 3UE, Aberdeen, Scotland, UK "Cuesta Ciscar, Angel" [email protected] The effect of the nature of the electrolyte cation on the activity and product selectivity of the electrocatalytic reduction of CO2 is well known [1]. Differences in the cation’s buffering capacity through hydrolysis of its solvation shell, that would lead to differences in the increase of the local pH at the interface during the electroreduction of CO2 have been suggested as the source of the above-mentioned cation-dependent activity and selectivity [2], and recently we have provided experimental evidence that the local pH during the reaction is indeed cation dependent [3]. Other explanations of cation effects on CO2 reduction include changes in adsorption energies of adsorbed intermediates due to cation-dependent polarization of adsorbed CO [4] and cation dependent degrees of hydrogen bonding of interfacial water to adsorbed CO [5] (the key intermediate in the reduction of CO2 to hydrogenated products). These effects can only be understood and controlled if the cation’s effect on the interfacial potential distribution is known. Using CO adsorbed on Pt as a probe molecule, and combining IR spectroscopy, capacitance measurements and ab initio molecular dynamics , we show that the cation size determines the location of the outer Helmholtz plane (OHP), whereby smaller cations increase not just the polarisation but, most importantly, the polarizability of adsorbed CO (COad) and the accumulation of electronic density on the oxygen atom of COad. This strongly affects its adsorption energy, the degree of hydrogen bonding of interfacial water to COad and the degree of polarisation of water molecules in the cation’s solvation shell, all of which can deeply affect the subsequent steps of the CO2RR. A parallel study using Au electrodes in acetonitrile in the potential region where CO2 reduction occurs leads to similar results. We find that the rate of change of the stretching frequency of adsorbates with potential, as well as the interfacial capacitance, are strongly dependent on the size of the electrolyte cation. In this case, the correlation between these two magnitudes is excellent, again suggesting that both are determined by the separation between the electrode surface and the OHP.

References

[1] A. Murata, Y. Hori, Product Selectivity Affected by Cationic Species in Electrochemical Reduction of CO2 and CO at a Cu Electrode, Bull. Chem. Soc. Jpn. 64 (1991) 123–127. [2] M.R. Singh, Y. Kwon, Y. Lum, J.W. Ager, A.T. Bell, Hydrolysis of Electrolyte Cations Enhances the Electrochemical Reduction of CO2 over Ag and Cu, J. Am. Chem. Soc. 138 (2016) 13006–13012. [3] O. Ayemoba, A. Cuesta, Spectroscopic Evidence of Size-Dependent Buffering of Interfacial pH by Cation Hydrolysis during CO2 Electroreduction, ACS Appl. Mater. Interfaces. 9 (2017) 27377–27382. [4] E. Pérez-Gallent, G. Marcandalli, M.C. Figueiredo, F. Calle-Vallejo, M.T.M. Koper, Structure- and Potential- Dependent Cation Effects on CO Reduction at Copper Single-Crystal Electrodes, J. Am. Chem. Soc. 139 (2017) 16412–16419. [5] J. Li, X. Li, C.M. Gunathunge, M.M. Waegele, Hydrogen bonding steers the product selectivity of electrocatalytic CO reduction, Proc. Natl. Acad. Sci. U. S. A. 116 (2019) 9220–9229. [6] G. Hussain, L. Pérez-Martínez, J.-B. Le, M. Papasizza, G. Cabello, J. Cheng, A. Cuesta, The potential profile across the electrode-electrolyte interface: cation size effects and implications for CO2 electrocatalysis, Electrochim. Acta 327 (2019) 135055.

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Tracking Changes in Surface Chemistry and Structure of Supported IrOx Nanoparticles in Acidic Oxygen Evolution Reaction Conditions

F. Maillard,a S. Abbou,a V. Martin,a R. Chattot,a F. Claudel,a and L. Dubaua

a Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP, LEPMI, 38000, Grenoble, France frederic.maillard@ grenoble-inp.fr

Advanced materials are needed to meet the requirements of water electrolysers designed for harvesting renewable electricity, and converting this electricity into molecular hydrogen (H2) and molecular oxygen (O2). In particular, polymer electrolyte membrane water electrolyzer devices would benefit from a reduction in the size of iridium oxide particles used to electrocatalyze the oxygen evolution reaction (OER) at the anode. Nevertheless, this strategy requires developing electron conducting, high surface area and stable supports. Herein, we synthesized IrOx nanoparticles, supported them onto doped SnO2 aerogels, and assessed their electrocatalytic activity towards the OER and their resistance to corrosion in acidic media ex situ and in situ (by means of a flow cell connected to an inductively-coupled mass spectrometer, FC-ICP-MS). The FC-ICP-MS results show that the long-term OER activity of IrOx/doped SnO2 aerogels is controlled by the resistance to corrosion of the doping element, and by its concentration in the host SnO2 matrix. In particular, we provide evidence that Sb-doped SnO2 supports continuously dissolve while Ta-doped or Nb-doped SnO2 supports are stable under acidic OER conditions. These results shed fundamental light on the complex and dynamic equilibrium existing between SnO2 and the doping element oxide in OER conditions.

Figure 1. Transmission electron microscopy of IrOx nanoparticles supported on: a) ATO-10, b) TaTO-2.5, c) TaTO-5 and d) TaTO-18. e), f) and g) correspond to time- and element- resolved materials dissolution during oxygen evolution reaction.

References (1) Claudel, F.; Dubau, L.; Berthomé, G.; Solà-Hernández, L.; Beauger, C.; Piccolo, L. ; Maillard, F. ACS Catal. 2019, 9, 4688. (2) C. Daiane de Ferreira, F. Claudel, V. Martin, R. Chattot, S. Abbou, K. Kumar, I. Jiménez- Morales, S. Cavaliere, D. Jones, J. Rozière, L. Solà-Hernandez, C. Beauger, M. Faustini, J. Peron, B. Gilles, C. Beauger, L. Piccolo, F. H. Barros de Lima, L. Dubau, F. Maillard, ACS Catal. 2021, 11, 4107.

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Bipolar Electrochemistry: the True Renewal of an Old Technique

Laurent Bouffier, Dodzi Zigah, Stéphane Arbault, Neso Sojic and Alexander Kuhn

University of Bordeaux, CNRS, Bordeaux INP, ISM, UMR-5255, F-33400 Talence, France [email protected]

Bipolar electrochemistry (BPE) is an old phenomenon that is known for decades but was for long restricted to specific applications such as electrolysis, corrosion or batteries. Recently, BPE has been rediscovered and has found new applications especially in materials science and analytical chemistry. There are several experimental setups but in most cases, a piece of conducting materials is immersed inside an electrolyte and submitted to an external electric field. The interfacial polarization potential enables the promotion of electrochemical processes on both sides of the object where oxidation and reduction reactions are decoupled in space. It is noteworthy that there is no direct ohmic contact between the power supply and the electrode making BPE a true wireless technique. At last but not least, BPE can be considered as a key method to break symmetry in chemical systems.

Our group has started to investigate BPE about ten years ago focusing on three main applications:  The design of asymmetric (Janus) particles and anisotropic surfaces1-4  The use of bipolar electrodes as analytical platforms5–7  The design and/or actuation of roving systems through BPE8–10

Representative examples will be selected in order to illustrate the versatility of BPE, focusing particularly on new applications that are enable by BPE while they cannot be achieved by conventional electrochemistry.

References (1) Loget, G.; Roche, J.; Gianessi, E.; Bouffier, L.; Kuhn, A. J. Am. Chem. Soc. 2012, 134, 20033. (2) Roche, J.; Loget, G.; Zigah. D.; Fattah, Z.; Goudeau, B.; Arbault, S.; Bouffier, L.; Kuhn, A. Chem. Sci. 2014, 5, 1961. (3) Bouffier, L.; Reculusa, S.; Ravaine, V.; Kuhn, A. ChemPhysChem 2017, 18, 2637. (4) Malytska, I; Doneux, T.; Bougouma, M.; Kuhn, A. ; Bouffier, L. J. Phys. Chem. C 2019, 123, 5647. (5) Bouffier, L.; Doneux, T.; Goudeau, B.; Kuhn, A. Anal. Chem. 2014, 86, 3708. (6) Sentic, M.; Arbault, S.; Bouffier, L.; Manojlovic, D.; Kuhn, A.; Sojic, N. Chem. Sci. 2015, 6, 4433. (7) Dauphin, A.; Arbault, S.; Kuhn, A.; Sojic, N.; Bouffier, L. ChemPhysChem. 2020, ASAP. (8) Sentic, M.; Arbault, S.; Goudeau, B.; Manojlovic, D.; Kuhn, A.; Bouffier, L.; Sojic, N. Chem. Commun. 2014, 50, 10202. (9) Fattah, Z.; Bouffier, L.; Kuhn, A. Appl. Mater. Today 2017, 9, 259. (10) Salinas, G.; Dauphin, A.; Colin, C.; Villani, E.; Arbault, S. Bouffier, L. Kuhn, A. Angew. Chem. Int. Ed. 2020, ASAP.

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Electrocatalysis on shaped metal nanoparticles: recent advances and remaining challenges

Francisco J. Vidal-Iglesias, Vicente Montiel, Juan M. Feliu, and José Solla-Gullón Institute of Electrochemistry, University of Alicante, Apdo 99, 03080 Alicante, Spain [email protected]

The incorporation of shape-controlled metal nanoparticles in Electrocatalysis is contributing significantly to a better understanding of the correlations between surface structure and electrochemical reactivity at the nanoscale [1-3]. In this communication, we will report some of the basic requirements to properly use these shaped metal nanoparticles in electrochemical reactions. Also, the importance of surface cleaning [4] and particle shape-surface structure stability [5], among others, will be discussed. Then, we will highlight some recent advances in the application of these shaped nanomaterials for different electrochemical reactions of interest [6-8]. Finally, we will present some of the most important challenges on this topic.

References

(1) Solla-Gullón, J.; Vidal-Iglesias, F. J.; Feliu, J. M. Annu. Rep. Prog. Chem., Sect. C: Phys. Chem., 2011, 107, 263. (2) You, H.; Yang, S.; Ding, B.; Yang, H. Chem. Soc. Rev., 2013, 42, 2880. (3) Kleijn, S. E. F.; Lai, S. C. S.; Koper, M. T. M.; Unwin, P. R. Angew. Chem. Int. Ed., 2014, 53, 3558. (4) Montiel, M.A.; Vidal-Iglesias, F.J.; Montiel, V.; Solla-Gullón, J. Curr. Opin. Electrochem., 2017, 1, 34. (5) Arán-Ais, R. M.; Solla-Gullón, J.; Herrero, E.; Feliu J. M. J. Electroanal. Chem., 2018, 808, 433. (6) García-Cruz, L.; Montiel, V.; Solla-Gullón, J. Physical Sciences Reviews, 2018, 4, 20170124. (7) Rizo, R.; Arán-Ais, R. M.; Padgett, E.; Muller, D. A.; Lázaro, M. J.; Solla-Gullón, J.; Feliu, J. M.; Pastor, E.; Abruña, H. D. J. Am. Chem. Soc., 2018, 140, 3791. (8) Antoniassi, R. M.; Erikson, H.; Solla‐Gullón, J.; Torresi, R. M.; Feliu, J. M. ChemElectroChem, 2021, 8, 49.

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Electrochemical Detection and Characterization of Soft Micro- and

Nano-Particles by Impact Experiments on Liquid|Liquid Interfaces Eduardo Laborda, Angela Molina, Francisco Martínez-Ortiz

Departamento de Química Física, Facultad de Química, Regional Campus of International Excellence “Campus Mare Nostrum”, Universidad de Murcia, 30100 Murcia, Spain [email protected]

The electrochemical detection and characterization of individual (sub)micrometric entities in solution upon collision at a biased solid microelectrode is a major research field that has provided novel and powerful methods for sizing and characterizing particles of very different nature: metallic, inorganic, organic and “soft” (eg., viruses, vesicles and emulsion droplets) 1. Within this context, the suitability of employing ion transfer processes across externally polarized ITIES (interfaces between two immiscible liquid electrolytes) for the electrochemical detection of individual particles has been recently proposed and assessed 2, noting the advantages that such interfaces can offer (reproducibility, absence of defects, mechanical flexibility, easy-to-modify), as well as their interest as biomimetic platforms. Different ITIES-based strategies recently developed will be discussed in this presentation (Figure 1). In the simple ion-transfer approach (Figure 1a), particles containing some ionic load are detected by the selective and quantitative interfacial transfer of one of the ions released upon their collision and fusion with the interface, which is conveniently polarized attending to the transfer Gibbs energy. As a result, a net charge transfer between the two phases takes place in each collision and a spike on the current-time response is obtained. From the value of the charge under the spike, the size of the particles or the concentration of their ionic load can be determined. A second approach under development will also be presented, with facilitated ion transfers as detection principle (Figures 1b and 1c). This expands the applicability of impact experiments at ITIES to situations where a suitable ‘ionic marker’ that transfers within the polarization window is not available. Thus, the charge transfer can be triggered by a ionophore present either at the particle (eg., emulsifying agents) or in the emulsion phase.

Figure 1. Schematics of the (a) simple ion-transfer and (b, c) facilitated ion-transfer strategies for the individual detection of soft particles at ITIES and of (d) the current-time response.

Acknowledgements Fundación Séneca - Agencia de Ciencia y Tecnología Región de Murcia (19887/GERM/15).

References (1) Xu, W.; Zou, G.; Hou, H.; Ji, X. Small 2019, 15, 1804908. (2) Laborda, E.; Molina, A.; Espín, V. F.; Martínez‐Ortiz, F.; García de la Torre, J.; Compton, R. G. Angewandte Chemie, 2017, 129, 800.

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Durability studies of platinum group metal-based carbon-supported nanoparticles in alkaline environments

Huong Doan, Clémence Lafforgue and Marian Chatenet

Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP*, LEPMI, 38000 Grenoble, France *Institute of Engineering and Management Univ. Grenoble Alpes [email protected]

Alkaline fuel cells and alkaline water electrolyzers are robust industrial technologies of the so- called the hydrogen economy. Although these systems are often presented as being compatible with platinum-group metal (PGM)-free electrocatalysts, most systems still use PGM, in particular at the hydrogen electrode. The common belief states that stability issues of the electrocatalysts is minor in alkaline-based versus proton-exchange membrane-based systems, owing to larger stability of many metals and oxides at high pH 1. The present presentation highlights that this fact is not granted for carbon-supported Pt and Pd nanoparticles (NPs): accelerated stress tests in dilute alkali aqueous solutions lead to pronounced electrochemical surface area (ECSA) losses, associated to major detachment of the Pt (and Pd) NPs from the carbon support 2,3. These degradations are neither induced by major corrosion of the metal NPs nor of the carbon support, as revealed by identical-location transmission electron microscopy (ILTEM). In situ Fourier-transform infrared spectroscopy and (pseudo) CO-stripping experiments show that the Pt (Pd) NPs do catalyze the initial stages of carbon support corrosion (carbon surface oxides form, evolve into CO2, then into carbonate anions), which destroys the link between the metal NPs and the carbon support, hence promoting the NPs detachment, and associated loss of ECSA 4 or of catalytic activity. Although not suppressed, the process is slower in the interface with a solid alkaline electrolyte (anion-exchange membrane), because the counter-cation of the OH- species are immobilized on the polymer backbone and cannot trigger carbonates’ precipitation 5. Using less noble electrocatalysts (e.g. Ni-based 6) can mitigate such degradations, opening the way to still active and more durable electrocatalyst for alkaline fuel cells and electrolyzers.

(1) Pourbaix, M. Atlas of Electrochemical Equilibria in Aqueous Solutions; National Association of Corrosion Engineers: Houston, 1979. (2) Zadick, A.; Dubau, L.; Zalineeva, A.; Coutanceau, C.; Chatenet, M. When cubic nanoparticles get spherical: An Identical Location Transmission Electron Microscopy case study with Pd in alkaline media. Electrochem. Commun. 2014, 48, 1-4. (3) Zadick, A.; Dubau, L.; Demirci, U. B.; Chatenet, M. Effects of Pd Nanoparticle Size and Solution Reducer Strength on Pd/C Electrocatalyst Stability in Alkaline Electrolyte. J. Electrochem. Soc. 2016, 163, F781-F787. (4) Lafforgue, C.; Maillard, F.; Martin, V.; Dubau, L.; Chatenet, M. Degradation of Carbon- supported Platinum Group Metal Electrocatalysts in Alkaline Media Studied by in situ Fourier- Transform Infrared Spectroscopy and Identical-Location Transmission Electron Microscopy. ACS Catal. 2019, 9, 5613−5622. (5) Lafforgue, C.; Chatenet, M.; Dubau, L.; Dekel, D. R. Accelerated Stress Test of Pt/C Nanoparticles in an Interface with an Anion-Exchange Membrane—An Identical-Location Transmission Electron Microscopy Study. ACS Catal. 2018, 8, 1278-1286. (6) Zadick, A.; Dubau, L.; Artyushkova, K.; Serov, A.; Atanassov, P.; Chatenet, M. Nickel-based electrocatalysts for ammonia borane oxidation: enabling materials for carbon-free-fuel direct liquid alkaline fuel cell technology. Nano Energy 2017, 37, 248-259.

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Using Quinones as Redox Carriers to Harvest Photosynthetic Electrons from Algae Suspension

Frédéric Lemaîtrea

a PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 24, rue Lhomond, 75005 Paris, France [email protected].

In the context of renewable energies, taking benefits from sunlight remains an important issue. In this respect, photosynthesis is an inspiring process since it is used by plants and algae to harness energy from sun and to eventually synthesize carbohydrates. Using natural photosynthesis as a photochemical converter is therefore a quite recent and burgeoning field. Indeed, after light capture, the photosynthetic chain results in several electron transfers along the photosynthetic chains that lead to two separate reactions (water oxidation and carbon dioxide reduction). Diverting a fraction of this electron flow is thus expected to produce bioelectricity.[1]

To do this, a collecting electrode needs to be used to harvest the photosynthetic electrons. However, it raises the question of the electron transport ways between the photosynthetic chain and the electrode. This is why many strategies have been developed over recent years in terms of biological targets (isolated photosystems, thylakoid membranes, intact living organisms), experimental configurations (adsorption vs suspension) or presence of redox carriers (conducting polymers, soluble mediators…).[1] This talk will be devoted to the strategy implemented in the laboratory that is to consider microalgae suspension with exogenous quinones as electron shuttles[2] within a spectroelectrochemical cell.[3-6] By means of fluorescence and electrochemistry techniques, advantages and drawbacks of this strategy will be described and discussed.[7, 8]

References [1] Grattieri, M. et al. Chem. Commun. 2020, 56, 8553. [2] Longatte, G. et al. Biophys. Chem. 2015, 205, 1. [3] Longatte, G. et al. Electrochim. Acta 2017, 236, 337. [4] Fu, H.-Y. et al. Nat. Commun. 2017, 8, 15274. [5] Sayegh, A. et al. Electrochim. Acta. 2019, 304, 465-473. [6] Beauzamy, L. et al. Anal. Chem. 2020, 92, 7532. [7] Longatte, G. et al. Chem. Sci. 2018, 9, 8271. [8] Beauzamy, L. et al. Sustain. Energ. Fuels 2020, 4, 6004.

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Índices de reactividad en catalizadores de tipo M-N-C (M: Fe,Co) para la reacción de reducción de oxígeno.

F. Javier Recioa , Chistian Candia-Onfrayb, Ricardo Venegas,b Karina Muñoz-Becerrac, Nieves Menéndeza.

a Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, 28049 Madrid, España b Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Macul, Región Metropolitana, Santiago, Chile cUniversidad Bernardo O´Higgins. Av. Viel 1497, Santiago, Región Metropolitana, Chile [email protected]

Durante la última década los catalizadores pirolizados de tipo M-N-C (M: metal de transición) se han presentado como firmes candidatos para la sustitución de los catalizadores de base Pt en pilas de combustible. Estos catalizadores, además de su bajo costo, presentan una alta actividad catalítica tanto en medio ácido y como en básico frente a la reacción de reducción de oxígeno (RRO) [1]. En su estructura se presentan diferentes sitios activos, siendo los más catalíticos los de tipo MN4 (similar a los catalizadores moleculares de tipo metaloporfirina y ftalocianina). Sin embargo, el diseño de estos catalizadores presenta muchas limitaciones debido al proceso de síntesis a altas temperaturas. Con el fin de mejorar las rutas sintéticas, se han planteado diferentes índices de reactividad estructurales como la cantidad de nitrógeno piridínico o de especies de tipo MN4 presentes en el catalizador. Sin embargo, la influencia de estos parámetros estructurales es dependiente del pH del medio en el que se evalúa la catálisis.

En este trabajo se explora el uso del potencial redox del sitio activo (MN4) en el catalizador como índice de reactividad frente a la RRO (en medio ácido y básico), y la cantidad de nanopartículas metálicas presentes en el catalizador como índice para la selectividad de la RRO vía 4 e-. En el estudio se sintetizaron seis tipos de materiales pirolizados de Fe y Co usando diferentes precursores. Los resultados muestran como existe una relación lineal entre el potencial redox del centro activo frente a la actividad catalítica, donde la actividad frente a la RRO aumenta confirme el potencial redox se hace más positivo, y como disminuyendo la cantidad de nanopartículas en el material se aumenta la selectividad de la reacción vía 4e-. En base a estos resultados experimentales y a cálculos teóricos mediante DFT se proponen los modelos de sitios catalíticos más activos para la RRO en medio ácido vía 4e-.

[1]. Strickland K, Miner E, Jia Q, Tylus U, Ramaswamy N, Liang W, Sougrati MT, Jaouen F, Mukerjee S. Nature Communications 2015, 6:7343

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Overview and outlook of the strategies devoted to electrofluorescence surveys for cell secretion analysis

Manon Guille-Collignon

Physical and biological chemistry of living matter Pole, UMR PASTEUR, Chemistry Department, Ecole Normale Supérieure, PSL, Sorbonne Université, 75005 Paris, France. [email protected]

Secretion of biomolecules during intercellular communication is a fundamental biological field where physicochemical machinery mechanism is still source of controversy. For more than thirty years, three isolated real-time techniques have been developed at the single cell level: electrophysiology (patch-clamp), electrochemistry (amperometry) and fluorescence (total internal reflection fluorescence microscopy -TIRFM).(1, 2) Recently, electrochemistry- fluorescence is a promising and feasible combination for monitoring neurotransmission.(3, 4) This presentation especially focuses on this expected fruitful coupling strategy and new challenges of this strenuous quest. Analytical constraints and principles (experimental set-up configuration, use of transparent electrodes, microdevices design and properties, cell models choice, chemical nature and physicochemical properties of electrofluorescent probes) of the TIRFM-amperometry combination will be commented since its seminal implementation. A special attention will be paid about the design of new dual spectroelectrochemical biomolecules over the last decade (fluorescent neural markers, fluorescent adducts, false fluorescent neurotransmitters)(5) for the convenient fluorescence-electrochemistry association that led to important molecular contributions.(6) Despite significant advances, this challenging combinatorial research continues and new obstacles (like reaching in the same molecule adequate fluorescent, electrochemical and biological target properties) need to be overcome thus giving the impression that the final purpose is currently at the same time so close and so far.

(1) Liu, X.; Tong, Y.; Fang, P.-P. Trends Anal. Chem 2019, 113, 13-24 (2) Keighron, J. D.; Wang, Y.; Cans, A.-S. Annu. Rev. Anal. Chem 2020, 13, 16.11-16.23 (3) Gillis, K. D.; Liu, X. A.; Marcantoni, A.; Carabelli, V. Pfluegers Arch. Eur. J. Physiol 2018, 470, 97-112 (4) Liu, X. Q.; Savy, A.; Maurin, S.; Grimaud, L.; Darchen, F.; Quinton, D.; Labbe, E.; Buriez, O.; Delacotte, J.; Lemaitre, F.; Guille-Collignon, M. Angew. Chem. Int. Ed. 2017, 56, 2366- 2370 (5) Lee, M.; Gubernator, N. G.; Sulzer, D.; Sames, D. J. Am. Chem. Soc. 2010, 132, 8828-8830 (6) Pandard, J.; Pan, N.; Ebene, D. H.; Le Saux, T.; Ait-Yahiatène, E.; Liu, X.; Grimaud, L.; Buriez, O.; Labbé, E.; Lemaître, F.; Guille-Collignon, M. ChemPlusChem 2019, 84, 1578-1586

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Sustainable lithium production using battery materials and redox agents

Nuria Garcia-Araez

University of Southampton, SO17 1BJ, Southampton, United Kingdom [email protected]

The accelerating expansion in the use of lithium batteries requires an equally accelerating expansion in the production of lithium (Li2CO3) to feed in the production of battery materials. Due to the very long cycle life of lithium-ion batteries, the lithium supply cannot be fulfilled by battery recycling, and therefore, the development of new and sustainable methods of lithium production is urgently needed [1].

In 2012, Pasta et al. [2] first demonstrated that the high selectivity of battery materials towards lithium ion opens up new and exciting possibilities for lithium production, with unique advantages in terms of cost, environmentally friendliness, method simplicity and absence of production of waste chemical products. Pasta et al. demonstrated the use of electricity to drive the reactions of selective lithium sequestration in the battery materials and subsequent release producing a high purity lithium product.

In 2014, our group [3] showed that the reactions of lithium sequestration and release from battery materials can also be induced with redox agents, thus enabling extra design flexibility and enhanced reaction kinetics and lithium selectivity. And in recent work [4], we have found a new redox agent, Na2SO3, that brings additional advantages in terms of low cost, non-toxicity, low reagent consumption, fast kinetics of lithium sequestration, and formation of an innocuous reaction product (Na2SO4), as illustrated in figure 1.

Figure 1. (a) Illustration of the method of lithium production from brines using battery materials (LiFePO4) and redox agents. (b) Comparison of the composition of the extract and the mother natural brine, using Na2SO3 as redox agent.

References (1) E. Olivetti et al. Joule, 2017, 1, 1229–243. (2) Pasta et al. Energy Environ. Sci. 2012, 5, 9487–9491. (3) N. Intaranont et al. J. Mater. Chem. A, 2014, 2, 6374– 6377 (4) S. Perez Rodriguez et al. ACS Sustainable Chem. Eng, 2020, 8, 6243–6251. (5) V. Flexer et al. Sc. Total Environ., 2018, 639, 1188–1204.

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Hybrid Electronics Based on Photosynthetic Organisms

Vincent Noel,a Julie Pham,a Letissia Hamza,a Giorgio Mattana,a Eleni Stavrinidou2,b Benoit Piro,a Samia Zriga a Université de Paris, ITODYS, CNRS, UMR 7086, 15 rue J-A de Baïf, F-75013 Paris, France b Laboratory of Organic Electronics, Department of Science and Technology, Linköping University, SE‐601 74, Norrkoping, Swedenc Address, Address, Town, Country

[email protected]

Today, Nature is being used as an active part of technology and technology is being used to enhance Nature. In this work, we try to establish a revolutionary symbiosis between photosynthetic organisms and technology, and to rethink and re-establish the concept of green technology by merging the unique characteristics of plants with smart synthetic or biosynthetic materials and electronic devices. In a long-term application perspective, this bio-hybrid technology is foreseen to be integrated in urban settings, agriculture and forestry, for more efficient exploitation of the energy cycles of the ecosystem.

One interesting goal in this prospective research field is to succeed in the in-vivo inclusion, within a living plant, of organic semiconductors and organic functional materials to build energy systems using enzymatic biofuel cells and biosupercapacitors. We propose to use the internal structure of the plant (in particular, its vascular tissue) as a template to interconnect the two compartments of such fuel cells, so that the devices can exactly match the plant’s structure.

I will present the already achieved milestones such as the synthesis of redox and conductive materials, e.g. conducting polymers and osmium-based redox hydrogels, and the development of protocols for their in-vivo inclusion and electrochemical characterization. These preliminary results pave the way to the implementation of the bioelectronic devices within living plants.

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FLASH POSTER 01- Re bipyridine/Ionic liquid co-catalyst type interaction for enhanced electrochemical CO2 reduction

Elli Vichou,a,b Maria Gomez-Mingot,a Yun Xu-Li,a Marc Fontecavea, and Carlos M. Sanchez- Sanchezb

a Laboratoire de Chimie des Processus Biologiques, Collège de France, Sorbonne Université, CNRS UMR 8229, PSL Research University, 11 Place Marcelin Berthelot, Paris 75231 Cedex 05, France b Laboratoire Interfaces et Systèmes Electrochimiques, LISE - UMR 8235 CNRS, Sorbonne Université, Campus Pierre et Marie Curie, 4 place Jussieu, 75005 Paris, France Presenting author’s email: [email protected]

Carbon dioxide electroreduction is an approach that, not only allows exploiting a waste material to produce valuable fuels or other chemicals, but also constitutes a promising solution for storing the intermittent energy originating from renewable sources. In this regard, the use of molecular catalysts can be highly beneficial as their well-defined structure provides useful 1 insight into their CO2 electroreduction mechanism. Furthermore, they can easily be finely tuned through substitutions on the ligands to alter their catalytic properties. However, they are often limited by their extensive use in organic solvents. Ionic Liquids themselves have been proven to enhance CO2 reduction and can be explored as alternative solvent and supporting electrolyte systems 2 with a possible co-catalyst effect in the presence of a molecular catalyst. Nevertheless, so far few approaches have been made to test a molecular catalyst in an ionic liquid environment, though these results demonstrate benefits in terms of overpotential diminution and increased reaction rates. 3,4 In the present study we have selected the well- established CO2 reduction catalyst [Re(CO)3bpyCl], also known as Lehn’s catalyst, for its high selectivity towards converting CO2 to CO through a well-known mechanism and studied it in a series of Ionic Liquids in order to identify the resulting interaction and its effects on the overall catalytic activity. For this purpose we have principally selected imidazolium-based Ionic liquids, which belong to one of the better studied categories of ILs and a pyrrolidinium one and studied them in the presence of the rhenium catalyst through cyclic voltammetry and controlled potential electrolysis experiments, only to discover significant potential shifts and current density amelioration. Under catalytic conditions, we have observed an overall overpotential diminution of about 200 mV while obtaining similar current densities compared to control conditions with the principal reduction product remaining CO.

References: (1) Qiao, J.; Liu, Y.; Hong, F.; Zhang, J. Chem Soc Rev 2014, 43 (2), 631–675. (2) Sanchez-Sanchez, C. M. ; Encyclopedia of Interfacial Chemistry : Surface Science and Electrochemistry; Wandelt, K., Ed.; Elsevier, 2018, p 539–551. (3) Grills, D. C.; Matsubara, Y.; Kuwahara, Y.; Golisz, S. R.; Kurtz, D. A.; Mello, B. A. J. Phys. Chem. Lett. 2014, 5 (11), 2033–2038. (4) Choi, J.; Benedetti, T. M.; Jalili, R.; Walker, A.; Wallace, G. G.; Officer, D. L. Chem. - Eur. J. 2016, 22 (40), 14158–14161.

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FLASH POSTER 02- Investigating the reactivity of surface functionalization with ion-terminated using scanning electrochemical microscopy (SECM)

S. Bencherif1, J. Ghilane2, M. Mechouet1

1. University of Mouloud MAMMERI, Tizi-Ouzou, Department of chemistry, , Algeria, 2. University of Paris, 15 rue Jean-Antoine de Baïf, 75013, Paris, France Presenting author’s email: [email protected]

Surface modification with thin organic layers is essential to design materials with suitable properties or with operating functions for developing practical applications such as (supercapacitors, metal-air batteries; fuel cells, corrosion resistance...). In the present work, we focused on the grafting of thin film with ionic organic layer molecules covalently attached onto glassy carbon electrode. The attached layer has an imidazolium cation attached to the surface and labile anion within the film.[1] The generated layers were investigated using electrochemistry, surfaces analysis and SECM. The obtained results highlight the change in the SECM response depending on the used redox mediator, thus a positive feedback is observed for negatively charged mediator suggesting the anion exchange within the layer and the presence of 2D mediation within the layer. In addition, the ability to make anion exchange was further investigated. Indeed, the attached molecule based ionic liquid molecule was used as host guest platform for the electrochemical growth of metallic nanocluster (case of platinum, palladium). Finally, the generated hybrid layer were investigated using SECM and their catalytic activities toward hydrogen evolution reaction will be presented.

References: [1] Ghilane, J.; Trippe-Allard, G.; Lacroix, J. C. Electrochem commun. 2013, 27, 73-76.

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FLASH POSTER 03- Nitrogen doped carbon dots and poly (ionic liquid) as high efficient metal-free electrocatalyst for oxygen reduction reaction

Christine Ranjan,a Hyacinthe Randriamahazaka,a and Jalal Ghilane a

a Université de Paris, ITODYS, UMR 7086 CNRS, SIELE Group 15 rue Jean Antoine de Baïf 75013 Paris, France. Presenting author’s email: [email protected]

From the past few years, carbon based nanomaterials (N-doped carbon nanotube arrays, N- doped graphene, N-doped graphene nanoplatelets, etc.) have been widely studied as highly efficient catalyst for the oxygen reduction.(1) Recent studies on microwave assisted method demonstrate a supporting evidence for the formation of carbon quantum dots (CDs) from bio- abundant starting materials as glucose and amino acids.(2) Although there have been important research focusing on the N-doped carbon dots, their use in electrocatalysis toward oxygen reduction is still scanty. Meanwhile ionic liquids and its derivatives have been started to be used as additive for oxygen reduction. In this context, we develop facile route to synthetized N-doped few nanometer scale CDs by microwave assisted method as high efficient catalyst for ORR.(3) Our studies were demonstrated that the N-doped CDs synthetized in ionic liquid (1-ethyl-3- methylimidazolium) exhibit exceptional selectivity toward 2 electron pathway resulting production of hydrogen peroxide (95% ±2 % over a broad range of potential from 0.6 V to -0.2 V vs RHE).(3) In addition, we combined the polymer brushes based ionic liquid with N-CDs to made a new hybrid material and investigate the ORR. The poly(imidazolium) were used as a platform for host guesting N-CDs material and their electrocatalytic activity towards the oxygen reduction reaction was evaluated. The obtained results demonstrate that the synergetic effect is correlated to the chemical structure and the morphology of the immobilized polymer ionic liquid. Finally, the poly(IL) was demonstrated to be a powerful strategy for boosting the catalytic activity for a given carbon-dots catalyst towards efficient 4 electron ORR.(4)

References (1) Zhou, M.; Wang, H. L.; Guo, S. Chem. Soc. Rev. 2016, 45, 1273–1307. (2) Georgakilas, V.; J.A. Perman, J. A.; Tucek, J.; Zboril, R. Chem. Rev. 2015, 115, 4744– 4822. (3) Pham-Truong, T. N.; Petenzi, T.; Ranjan, C.; Randriamahazaka, H.; Ghilane, J. Carbon, 2018, 130, 544-552 (4) Pham-Truong, T.N.; Ranjan, C.; Randriamahazaka, H.; Ghilane, J. Catalysis Today, 2019, 335, 381-387.

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FLASH POSTER 04- Role of Biofilms in the performances of a fungal microbial fuel cell

Maxime PONTIE,a , Mehri SHABANI,a, Maxime VALAY,b, Christophe INNOCENT,c and Andriy YAROSCHUKd a Angers University, Faculty of Sciences, 2 Bd. Lavoisier, 49045 Angers cedex 01, France b OrigaLys ElectroChem SAS, 62A, Avenue de l’Europe, 69140 Rilleux-la-Pape, France c IEM, UMR CNRS 5635, 300 Avenue du Prof. Emile Jeanbrau, 34090 Montpellier, France d ICREA & Universitat Politècnica de Catalunya, Dept. of Chemical Engineering, Barcelona, Spain

Presenting author: [email protected]

Our research aimed to explore the biodegradation of organic micropollutants (i.e. diclofenac, acetaminophen) in a dual-chamber fungal microbial fuel cell (FMFC) recently developed (1). The microorganisms are of great advantage as they can be regenerated resulting in lower cost comparing to chemical ones. Also, no harmful by-products or wastes has been produced during the degradation process which makes MFCs an environmentally friendly way to generate energy. On one hand, biofilms deposited on electrodes (i.e. carbon felt) is very usable to oxidize + - micropollutants and generate H and e to reduce O2 in the cathodic compartment. On the other hand the cationic exchange membrane (CEM) will be covered by a biofilm, as illustrated by Fig.1 (a). It could cause the blockage in H+ migration mass transfer (see (2)).

Fig.1 : 2D scanning electronic microscpoy (SEM) images of Nafion 117 membrane used in a fungal microbial fuel cell : a- old membrane used in FMFC (10 days); b- pristine membrane

Furthermore, and unfortunately, SEM observations are a destructive tool for membrane. Further work in a near future will focus on the development of experimental and theoretical approaches using electrochemical impedance spectroscopy (EIS) as in situ tool for the detection of biofilm growth on CEM, in particular, for understanding its detrimental impact on limiting current density (3).

References (1) Shabani, M.; Pontié M. et al. J. Applied Electrochemistry, 2021, 51, 581 + ref. therein (2) Flimban, S.G.A. et al. Int. J. of Hydrogen Energy, 2020, 45, 13643. (3) Zhen, H., Mansfeld, F. Energy and Environt. Sci. 2009, 2, 215.

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FLASH POSTER 05- Understanding the photoelectrochemical response of Bi2WO6 /carbon electrodes upon varied illumination conditions

Getaneh Diress Gesesse, Alicia Gomis-Berenguer, Marie-France Barthe, Conchi Ania

CEMHTI (UPR 3079), CNRS, Université d’Orléans, 45071 Orléans, France

[email protected]

Semiconductor/carbon composites have been extensively studied in photoelectrocatalysis, in many cases showing an enhanced performance compared to the bare semiconductor. This behavior has been attributed to the role of the carbon additive in reducing the recombination of the photogenerated charge carriers, although the origin of such response and its correlation with the nature of the carbon material still remains unclear. To further clarify this, we have herein investigated the photoelectrochemical response of Bi2WO6/carbon electrodes using carbons of different electronic properties, composition, porosity and structure. Bi2WO6 was selected based on our previous studies indicating its good performance under simulated solar light [1]. Commercial TiO2 has been used as benchmark photoelectrocatalyst for comparison purposes. The semiconductor/carbon mixtures (ca. 2 wt.% of carbon) were prepared as indicated elsewhere [1]. For the electrochemical measurement, the electrodes were prepared by casting the mixture on ITO substrate via spin-coating technique and annealed at the required temperature to remove the solvent. The electrochemical measurements were carried out in a 3- electrodes cell with a flat quartz window, using 0.5 M Na2SO4 (pH 6) as electrolyte. The working electrode consisted of the materials casted on ITO substrate, graphite rod and Ag/AgCl (KCl saturated) were used as counter and reference electrodes, respectively. In order to investigate the electrochemical response of the prepared materials, different electrochemical techniques were applied: cyclic voltammetry, chronoamperometry and impedance spectroscopy. The transient photocurrent response at various bias potentials and the photopotential at dark and upon on/off illumination for several cycles were recorded. Under dark conditions, the voltammograms showed the characteristic fingerprint of the semiconductor with the accumulation and depletion zones, and the capacitive contribution the carbon material for the mixtures with carbons of a high nanoporous structure. More interestingly, the intensity of the photocurrent was enhanced in the presence of the carbon additives, compared to the response of the bare semiconductor. The magnitude of the photocurrent and its nature (cathodic/anodic) varied with the bias potential. As a general rule, the anodic photocurrent increased as the potential shifted towards more positive values. The enhanced photocurrent in the composite indicates a higher photogeneration (or lower recombination) of the charge carries in the electrodes during illumination. The effect was also observed when porous carbons with moderate electronic conductivity were used as additives, and it was more pronounced for carbons with a low functionalization degree. The photocurrent was reproducible upon various on/off illumination cycles.

References (1) Gomis-Berenguer, A.; Eliani, I.; Lourenço, V.F.; Carmona, R.J.; Velasco, L.F.; Ania C.O. Insights on the use of carbon additives as promoters of the visible-light photocatalytic activity of Bi2WO6. Molecules, Materials 2019, 12, 385.

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FLASH POSTER 06- Quantitative thermodynamics of solubilization of pH- sensitive, redox-flow battery relevant anthraquinones

Théophile Gaudin,a Raphaël Lebeufa, Véronique Nardello-Rataja and Jean-Marie Aubrya a Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181 – UCCS – Unité de Catalyse et Chimie du Solide, F-59000 Lille, France [email protected]

Redox flow batteries (RFBs) are secondary batteries in which the energy conversions are based on the reversible electrochemical reactions of two redox couples1. RFBs are ideally suited for relatively large stationary applications (capacities of 1 kWh to 10 MWh)2, among which is the highly relevant energy storage from intermittent sources such as solar or wind power3. The understanding of dissolution of renewable battery electrolytes as a function of pH, such as those of the anthraquinone family, often both sparingly soluble in water and acid/basic4, is of critical importance, in order to maximize achievable energy density and cell voltage. The impact of pH on the solubility is relevant in a variety of areas. For example, it has been studied in the pharmaceutical industry, where it has been found relevant for the preparation or administration of pH-sensitive drugs5. In addition, it is exploited to selectively precipitate inorganic anions such as Zn2+ or Cd2+6. But in the case of RFB, both neutral and salt form precipitations may be relevant, and to the best of our knowledge, the simultaneous study of these two phenomena has never been carried out. In this contribution, we interpret solubility-pH diagrams in terms of acid-base and dissolution phenomena, using a novel self-consistent algorithm. A surprising diversity of behaviors originates from moderate changes in the pKa, pKs and solubilities. We propose rules of thumb to anticipate solubility issues in RFB as a function of the thermodynamic understanding provided by our algorithm. From a purely predictive standpoint, nowadays, some methods exist to estimate pKa and solubility of neutral compounds. However, the ab-initio prediction of solubility products is still slightly out of reach in present time due to the difficulty of predicting the packing of organic salts into the solid phase. Nevertheless, our self-consistent algorithm paves the way to quantitatively predict solubility-pH curves for any molecule of interest, fully ab-initio, as soon as the solubility product becomes predictable. This work was financially supported by the Agence Nationale de Recherche (Grant number: ANR-19-CE05-0012), and has been partially funded by the CNRS Energy unit (Cellule Energie) through the project PEPS-Catether. References (1) Zhang, H.; Li, X.; Zhang, J., Redox Flow Batteries: Fundamentals and Applications. CRC Press: Boca Raton, 2018. (2) Service, R. F., Advances in flow batteries promise cheap backup power. Science 2018, 362 (6414), 508. (3) Wang, W.; Sprenkle, V., Redox flow batteries go organic. Nature Chem. 2016, 8 (3), 204-206. (4) Huskinson, B.; Marshak, M. P.; Suh, C.; Er, S.; Gerhardt, M. R.; Galvin, C. J.; Chen, X.; Aspuru-Guzik, A.; Gordon, R. G.; Aziz, M. J., A metal-free organic–inorganic aqueous flow battery. Nature 2014, 505 (7482), 195-198. (5) Avdeef, A., Solubility of sparingly-soluble ionizable drugs. Advanced Drug Delivery Reviews 2007, 59 (7), 568-590. (6) Burgot, J. L., Solubility and pH. In Ionic Equilibria in Analytical Chemistry, Springer: New York City, 2012; pp 633-658.

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Electron-Triggered Metamorphism in Adaptative Supramolecular Polymers

C. Kahlfuss,a E. Dumont,a E. Saint-Aman,c Y. Nassar,a S. Al Shehimy,a S. Chowdhury,a T. Gibaud,b D. Frath,a G. Demets,d F. Chevalliera and C. Buchera

a Lab. de Chimie UMR 5182 CNRS-Univ.Lyon, ENS de Lyon UCB-Lyon 1-France b Lab. de Physique, UMR 5672 CNRS-Univ.Lyon, ENS de Lyon UCB Lyon 1-France c Univ.Grenoble-Alpes, CNRS Département de Chimie Moléculaire ; Grenoble-France dDQ-FFCLRP, Universidade de São Paulo. RibeirãoPreto S.P. - Brazil

[email protected]

Stimuli-responsive self-assembled supramolecular materials are currently subject to intense research activity. The ability of supramolecular polymers to adapt to their environment and to evolve upon stimulation indeed make them perfect candidates for the development of “smart” materials for a variety of applications, including sensors, information displays, memories, probes, piezoelectric or mechanochromic devices. Light, pH and host-guest recognition processes are the most common stimuli used so far to trigger the association/dissociation or changes in the organization of molecular components involved in supramolecular materials. Such changes are conversely much more difficult to achieve when using more subtle constraints such as those involving electron transfers, although being essential to ensure the implementation of such materials in devices. Our group has been focusing over the past few years on the development of tailor-made redox- controllable molecular and supramolecular systems involving electrogenerated pi-radicals as key responsive and/or assembling elements [1,2]. In this lecture, we will focus on the physicochemical properties of a series of metal-ligand assemblies whose structure/formation/dissociation can be controlled with optical or electrical stimulus. The dynamic properties of these stimuli-responsive (supra)molecular architectures will mainly be discussed on the basis of electrochemical, spectroelectrochemical and ESR experiments supported by quantum chemical calculations [3-7].

References. (1) Kahlfuss, C.; Saint-Aman, E.; Bucher, C., Redox-controlled intramolecular motions triggered by π-dimerization and πmerization processes. In Organic Redox Systems: Synthesis, Properties, and Applications, Nishinaga, T., Ed. John Wiley and sons: New-York, 2016; pp 39. (2) Correia, H. D.; Chowdhury, S.; Ramos, A. P.; Guy, L.; Demets, G. J.-F.; Bucher, C., Polym. Int. 2019, 68, 572. (3) Kahlfuss, C.; Gruber, R.; Dumont, E.; Royal, G.; Chevallier, F.; Saint-Aman, E.; Bucher, C., Chem. Eur. J. 2019, 25, 1573. (4) Brunet, G.; Suturina, E. A.; George, G. P. C.; Ovens, J. S.; Richardson, P.; Bucher, C.; Murugesu, M., Chem. Eur. J. 2020, 26 (69), 16455 (5) Chowdhury, S.; Nassar, Y.; Guy, L.; Frath, D.; Chevallier, F.; Dumont, E.; Ramos, A. P.; Demets, G. J.-F.; Bucher, C., Electrochim. Acta 2019, 316, 79. (6) Kahlfuss, C.; Gibaud, T.; Denis-Quanquin, S.; Chowdhury, S.; Royal, G.; Chevallier, F.; Saint-Aman, E.; Bucher, C., Chem. Eur. J. 2018, 24 (49), 13009. (7) Kahlfuss, C.; Chowdhury, S.; Carreira, A. F.; Grüber, R.; Dumont, E.; Frath, D.; Chevallier, F.; Eric Saint, A.; Bucher, C., Inorg. Chem. 2021, 60 (6), 3543. (8) Kahlfuss, C.; Denis-Quanquin, S.; Calin, N.; Dumont, E.; Garavelli, M.; Royal, G.; Cobo, S.; Saint-Aman, E.; Bucher, C., J. Am. Chem. Soc. 2016, 138, 15234.

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Electrochemical Enhanced Raman Spectroscopy (TERS, SHINERS) Toward the characterization of functionnal nanomaterials in operation

Alice Fiocco,a Aja Pavlic,a Antonin Gajan,a Laure Fillaud,a Julien Demeaux,b Jean-Marc Noel,c Emmanuel Maisonhaute,a Ivan T. Lucas,a

a LISE, Sorbonne Université, F-75005 Paris, France b Saft, Corporate Research, 33074, Bordeaux, France c Itodys, Univ. Paris, 75013 Paris, France [email protected]

Tip-Enhanced Raman Spectroscopy (TERS) introduced in the late 90s, almost remained at the conceptual stage of its development for many years, being the privilege of only a handful of research groups worldwide. In recent years, its potential to analyze electrochemical systems and interfaces at the nanoscale has been demonstrated, opening the way to the study of functional nanomaterial (energy, catalysis) under the condition of their operation. Different approaches have been developed in LISE for the characterization of electroactive systems (molecules, surfaces, nanoparticles) under polarization, e.i. STM-TERS & AFM-TERS [1, 2] and more recently SHINERS. In this latter declination, Au@Si02 nanoparticles are used as plasmonic signal nanoamplifiers, enabing the extraction of Raman signatures of weak Raman scatterers even in operando conditions. SHINERS was succesfully implemented operando to characterize interfaces (SEI) developped on high-voltage electrode materials for Li-ion batteries.[3] References: [1] Touzalin T, Joiret S, Lucas I.T., Maisonhaute E, “Electrochemical tip-enhanced Raman spectroscopy imaging with 8 nm lateral resolution”, Electrochem. Comm. 2019, 108, 106557 [2] Touzalin T., Dauphin A.L., Joiret S., Lucas I.T., Maisonhaute E., “Tip enhanced Raman spectroscopy imaging of opaque samples in organic liquid”, Phys. Chem. Chem. Phys., 2016, 18, 15510. [3] Gajan, A., Lecourt, C., Bautista, B. E. T., Fillaud, L., Demeaux, J., Lucas, I. T. “Solid Electrolyte Interphase Instability in Operating Lithium-Ion Batteries Unraveled by Enhanced-Raman Spectroscopy”. ACS Energy Letters 2021, 6, 1757.

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Obtaining Functional Monolayer by Aryl Diazonium Reduction

Yann R. Leroux

Univ. Rennes, CNRS, ISCR – UMR 6226, Campus de Beaulieu, F-35000 Rennes, France [email protected]

Since the earlier works of Whitesides and coworkers [1] concerning the preparation of Self- Assembled Monolayers (SAMs) on gold substrates, SAMs represent one of the best systems available for studying the contribution of molecular structure and composition to the macroscopic properties of materials. Unfortunately, this technique cannot be extended to other materials and provides weakly robust interfaces, which make them suitable for laboratory research but limit their use in real applications. Since its discovery in the beginning of the 90s, [2] the (electro-) reduction of aryl diazonium salts is now often used as surface modification technique. The main advantages of this technique are: i) it produces highly robust interfaces and ii) it can be applied to a wide range of materials (conductors, semiconductors, insulators). Its major drawbacks remain in the difficulties of controlling the vertical extent of the reaction. Aryl radicals that are produced during this process are highly reactive species and they rapidly add to the substrate electrode where they are produced, but also react with the already-grafted aryl layers. This generally leads to multiple attachments and formation of disordered poly-aryl multilayers. Only recently, a few research groups [3] proposed new methods to achieve monolayers onto carbon surfaces, using the electro-reduction of aryl diazonium salt. These new approaches can lead to the development of carbon materials as substrates supporting functional monolayers and can find applications in electrochemical (bio) sensors, analytical chemistry or molecular electronics. In this presentation, a brief overview of the different methods used to control the thickness and organization of electro-grafted organic layer by the reduction of aryl diazonium salts will be presented. We will focus more on the strategies developed in our laboratories [4] and on examples where such strategies have been used for applications.

References

(1) a) Bains, C. D.; Evall, J.; Whitesides, G. M. J. Am. Chem. Soc. 1989, 111, 7155-7164. b) Bains, C. D.; Whitesides, G. M. J. Am. Chem. Soc. 1989, 111, 7164-7175. (2) Pinson, J.; Podvorica, F. Chem. Soc. Rev. 2005, 34, 429-439. (3) Breton, T.; Downard, A. J. Aust. J. Chem. 2017, 70, 960–972. (4) a) Leroux, Y. R.; Fei, H.; Noel, J.-M.; Roux, C.; Hapiot, P. J. Am. Chem. Soc. 2010, 132, 14039-14041. b) Leroux, Y. R.; Hapiot, P. Chem. Mater. 2013, 25, 489-495. c) Lee, L.; Ma, H.; Brooksby, P. A.; Brown, S. A.; Leroux, Y. R.; Hapiot, P.; Downard, A. J. Langmuir 2014, 30, 7104-7111. d) Lee, L.; Leroux, Y. R.; Hapiot, P.; Downard, A. J. Langmuir 2015, 31, 5071-5077.

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Structure-reactivity effects of biomass-based hydroxyacids for sustainable hydrogen production by electrolysis

Daniel Martín-Yerga,a,b* Jai L. White,b Xiaowen Yu,c Irina Terekhina,c Gunnar Henriksson,d and Ann Cornellb

a Department of Chemistry, University of Warwick, CV4 7AL Coventry, UK b Department of Chemical Engineering, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden c Department of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden d Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, SE- 10044 Stockholm, Sweden [email protected]

Replacing fossil fuels is one of the greatest challenges for society to transition to clean and affordable energy. H2 is ultimately the cleanest form of energy and will play a significant role in a future sustainable energy system. Electrochemical water splitting is a promising technology for generation of H2 fuel. However, limiting factors of this technology are the high energy requirements and the sluggish kinetics of the anodic half-reaction, the oxygen evolution reaction (OER). Interestingly, the OER can be potentially replaced by oxidation of biomass- based compounds coming from renewable and sustainable sources. This alternative has a 3-fold advantage: a) the reaction thermodynamics are usually more favorable than for the OER, b) biomass-based products may be widely available as a low-value by-product in different industries, and c) products of this reaction may find further applications in other fields.

The most studied and promising biomass-based compounds for electrochemical production of 1 H2 are alcohols such as methanol, ethanol and glycerol. Other biomass-based compounds such as organic hydroxyacids are less studied for this purpose. These carboxylic acids, containing one or several hydroxyl groups, are widely available from nature or generated by industrial processes such as paper production and may also be attractive as anodic reactants for H2 production by electrolysis. However, a recurring issue for the electro-oxidation of hydroxyl- based organic compounds is the quick deactivation of electrocatalysts,2 preventing the attainment of high current densities required for industrial H2 production.

This work evaluates the electro-oxidation of two biomass-based organic hydroxyacids, lactic acid and gluconic acid, as anodic reactions for H2 production. A bimetallic PdNi electrocatalyst deposited on high surface-area Ni foam3 was used to enable the reaction at low potentials and achieving relatively high current densities. This study provides insights on how the chemical structure of these biomass-based hydroxyacids affects the electrochemical reactivity and, therefore, their possibilities to be used for efficient H2 production by electrolysis. References (1) Coutanceau, C., Baranton, S. WIREs Energy Environ. 2016, 5, 388-400. (2) Wang L., Lavacchi A., Bellini M. et al. Electrochim. Acta 2015, 177, 100-106. (3) Martín-Yerga D., Yu X., Terekhina I., Henriksson G., Cornell A., Chem. Commun. 2020, doi: 10.1039/D0CC01321H

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Physical distancing: an approach for obtaining (bi)functional monolayers from diazonium salts

Christelle Gautier, MOLTECH-Anjou - UMR CNRS 6200 - Université d’Angers, 2 boulevard Lavoisier, Angers, France [email protected]

Surface functionalization is often used for the preparation of nanomaterials with applications in various fields such as analysis, catalysis, or nano-electronics. To get a better understanding of the material’s behaviour, today’s major challenges no longer lie in only grafting species of interest, but in controlling the parameters governing their organization. In order to be usable in a wide range of media, the target systems require sustainable immobilization of the molecules on the substrate. Among existing surface modification methods, reduction of aryldiazonium cations represents a method of choice to form stable functional conductive materials. However, this efficient process also has serious disadvantages linked to the difficulty of controlling the layers formation. Several strategies allowing the grafting control, in terms of thickness, have been developed1,2 and the obtained results leave no room for doubt about the possibility of controlling the thickness of the layers. Although the grafting mechanism of isolated diazonium precursors is well understood, the simultaneous grafting of two different cations, leading to the elaboration of bifunctional surfaces, is still poorly studied and not mastered at all. One limitation concerns the control of the ratio of species on the surface since the grafting kinetics is partly governed by the reduction potential of the precursors: in most cases, the most easily reducible is predominantly fixed on the surface. Our strategy is to integrate an aliphatic spacer between the phenyl diazonium and an electroactive functional moiety (Figure 1). More than having a beneficial impact on the reduction potential of the diazonium cations, by erasing the electronic effect of the functional group on the diazonium function, it is also expected that a long alkyl chain could suppress the electron tunneling through the organic layer, thus stopping the grafting to produce compact monolayers.3

Figure 1. General design of diazonium precursors

Electrodes were functionalized by several diazonium precursors and characterized by cyclic voltammetry, quartz-crystal microbalance, atomic force microscopy and X-ray photoelectron spectroscopy. The impact of the aliphatic chain has been highlighted by comparing the properties of organic layers obtained from diazonium precursors with different chain lengths.

References (1) Combellas, C.; Kanoufi, F.; Pinson, J.; Podvorica, F. I. J. Am. Chem. Soc. 2008, 130, 8576-8577. (2) Pichereau, L.; López, I.; Cesbron, M.; Dabos-Seignon, S.; Gautier, C.; Breton, T. Chem. Commun. 2019, 55, 455-457. (3) Tanaka, M.; Sawaguchi, T.; Sato, Y.; Yoshioka, K.; Niwa, O. Langmuir 2011, 27, 170- 178.

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Ionic Liquids for electrochemical activation of CO2 and electrochromic devices

Gonzalo Guirado,a Iluminada Gallardo, a Silvia Mena a , Sara Santiago, a

a Departament de Química, Universitat Autònoma de Barcelona, 08193- Bellaterra (Barcelona), 08193, Spain. [email protected]

Ionic liquids (ILs) are solvents composed exclusively by ions. Those solvents are one of the most popular green electrochemical solvents due to a negligible vapor pressure, electrochemical stability and relatively high ionic conductivity. [1] In this communication different applications of the synergistic use of electrochemical techniques and ionic liquids will be discussed. The first part of the talk would be devoted to use altogether of “green technologies” (electrochemistry and ILs) for the design of environmentally friendly routes thought electrochemical activation and capture of CO2.[2] Finally, the second part aims to demonstrate the use of ionic liquids in polymeric matrices (ionogels) doped with smart molecules for the design and manufacture of solid-multiresponsive and electrochromic materials.[3] The facile preparation, flexibility, mechanical strength, self-standing nature and shapeability of ionogels, make these materials promising candidates for the fabrication of a range of stimuli-sensitive systems and devices for optoelectronic applications (e.g., smart displays, chemical sensors, security inks, data storage).

ACKNOWLEDGMENTS The authors thank the Ministerio de Ciencia e Innovación of Spain for financial support though the projects CTQ 2015-65439-R and PID2019-106171RB-I00

References (1) Reche, I.; Gallardo, I.; Guirado, G. Phys. Chem. Chem. Phys. 2015, 17, 2339 (2) Mena, S.; Guirado, G. J. C 2020, 6, 34. 1-21 (3) Santiago, S.; Muñoz-Berbel, X.; Guirado, G.; J. Mol. Liq. 2020, 318, 114033

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Electrochemical technologies facing the challenge of treating bio-sanitary effluents

Cristina Sáez,a Angela Moratallaa, Miguel Herraiz-Carbonéb, Salvador Cotillasb, Engracia Lacasab, Pablo Cañizaresa, Manuel A. Rodrigoa

a Faculty of Chemical Sciences and Technologies, Ciudad Real, Department of Chemical Engineering, Avenida Camilo José Cela 12, 13071 Ciudad Real, Spain bSchool of Industrial Engineering, Albacete, Department of Chemical Engineering, Avenida de España S/N, 02071 Albacete, Spain. [email protected]

In last decade, treatment of hospital and bio-sanitary wastewater has been the target of many researches, using biological and chemical oxidation treatments, membrane processes or Advanced Oxidation Processes (1). Among them, Electrochemical Advanced Oxidation Processes (EAOPs) seem to be a good alternative to reduce the risk of hospital effluents but more scientific effort is needed for large-scale application. Among these risky hospital effluents, urines are one of the most dangerous liquid wastes due to the variety and concentration of pharmaceuticals and pathogens contained. Thus, although urine accounts for only a small percentage of the total wastewater amount, the concentration of its contaminants may be up to 3-fold higher than that found in overall hospital wastewater. This detail makes urine treatment a key objective for reducing the environmental and health impact of hospital effluents and, also, energy costs for downstream Wastewater Treatment Plants (WWTPs). Therefore, the goal of this work is the design of a process based on electrochemical technologies to reduce the environmental and sanitary impact of hospital effluents by direct treatment of hospital urine, due to their chemical and biological risk. It does not intend to evaluate the best electrochemical technology for the complete degradation of pharmaceuticals (which implies a higher energy consumption and therefore a higher cost), but to implement a technology for the conversion of potentially hazardous pharmaceuticals into other less hazardous intermediate compounds, avoiding the generation of undesirable by-products and being able to reach also adequate levels of disinfection. To do this, the development of efficient flow-through electrochemical reactor for its use in electrooxidation and/or electroFenton processes has been carried out. This entails not only the implementation of a suitable anode but also the synergistic use of the cathode reaction and the promotion of mediated oxidation processes in the bulk during the treatment. In addition an efficient mechanical design of the cell and a careful choice of the operation conditions are critical to achieve good performance

References (1) Ganiyu, S.O.; van Hullebusch, E.D., Cretin, M.; Esposito, G.; Oturan, M.A. Separation and Purification Technology 2015, 156, 891. (2) Cotillas, S.; Lacasa, E,; Sáez, C.; Cañziares, P.; Rodrigo, M.A. Chemical Engineering Journal, 2018, 606.

Acknowledgements This work is supported by Junta de Comunidades de Castilla-La Mancha and European Union through the project SBPLY/17/180501/000396.

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Coupling fluorescence microscopy with electrochemistry or how to use optics to watch the electrochemical reaction at the micron scale

Fabien Miomandre, Laetitia Guerret-Legras, and Jean-Frédéric Audibert a ENS Paris-Saclay, 4 avenue des Sciences, 91190 Gif/Yvette, France [email protected]

Fluorescence and electrochemical techniques are often used as complementary tools to investigate various phenomena occurring on a substrate in contact with an electrolyte. These two techniques can be easily implemented at the micron scale using a fluorescence microscope and/or ultramicroelectrodes positioned in the vicinity of the substrate like in the SECM configuration1. Fluorescence microscopy offers the possibility to image the phenomenon and detect species with high sensitivity. Electrochemistry can be used either as a complementary detection technique (e.g. for species identification) or to trigger the phenomenon to investigate2. Our group recently demonstrated that SECM and fluorescence microscopies can be used as combined techniques using a fluorophore as the redox mediator3. In this communication, we will show how this coupling offers the opportunity to position an ultramicroelectrode close to the substrate through optical approach curves which are more accurate than the classical electrochemical ones. The appropriate choice of the mediator allows the user to work either in organic or aqueous medium4. Finally, the use of a pulsed laser source enables to follow the variation of the excited state lifetime, bringing important information to elucidate the mechanisms involved.

Combined SECM-Fluorescence microscopy set-up

References 1. Salamifar, S. E.; Lai, R. Y., Analytical Chemistry 2013, 85 (20), 9417-9421. 2. Bouffier, L.; Doneux, T., Current opinion in electrochemistry 2017. 3. Legras, L.; Audibert, J. F.; Dubacheva, G. V.; Miomandre, F., Chemical Science 2018, 9 5897. 4. Guerret-Legras, L.; Audibert, J. F.; Ojeda, I. M. G.; Dubacheva, G. V.; Miomandre, F., Electrochimica Acta 2019, 305, 370-377.

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Progress in Electro-Fenton Process and Related Technologies for Electrochemical Wastewater Treatment at Near-Neutral pH

Ignasi Sirés

Advanced water treatment is one of the most paradigmatic examples of applications that clearly distinguish electrochemistry among other chemistry branches. The production of highly reactive oxygen species on demand is feasible upon smart choice of electrode materials and reactor setup alongside the simple modulation of electrolytic conditions. Electro-Fenton (EF) process and related Fenton-based technologies outperform the other methods due to the massive generation of hydroxyl radicals in the bulk solution. However, for years their scale-up has been limited because of the strict restriction of the operation conditions, which required acid pH 3 to enhance the H2O2 decomposition and minimize the iron sludge accumulation. In addition, the two-electron oxygen reduction reaction (ORR) mostly relied on the use of unmodified carbonaceous materials, and the reactors basically mimicked those well established for electrooxidation and energy production. In this overview, our latest advances in EF process are presented, with focus on the strategies followed to treat refractory organic pollutants in urban wastewater at natural pH (i.e., near- neutral). Great results have been achieved using either homogeneous chelated iron1 or heterogeneous catalysts derived from metal-organic frameworks.2,3 The modification of carbons is a route to enhance the ORR,4 and decoration with Co-based nanparticles5 or the use of 3D cathodes6 has yielded very positive results. In parallel, the scale-up of this technology is being conveniently addressed.7

References (1) Ye, Z.; Brillas, E.; Centellas, F.; Cabot, P.L.; Sirés, I. Water Res. 2020, 169, 115219. (2) Ye, Z.; Padilla, J.A.; Xuriguera, E.; Brillas, E.; Sirés, I. Appl. Catal. B: Environ. 2020, 266, 115219. (3) Ye, Z.; Padilla, J.A.; Xuriguera, E.; Beltran, J.L.; Alcaide, F.; Brillas, E.; Sirés, I. Environ. Sci. Technol. 2020, doi:10.1021/acs.est.9b07604. (4) Chai, G.-L.; Hou, Z.; Ikeda, T.; Terakura, K. J. Phys. Chem. C 2017, 121, 14524. (5) Alcaide, F.; Álvarez, G.; Guelfi, D.R.V.; Brillas, E.; Sirés, I. Chem. Eng. J. 2020, 379, 122417. (6) Pérez, T.; Coria, G.; Sirés, I.; Nava, J.L.; Uribe, A.R. J. Electroanal. Chem. 2018, 812, 54. (7) Salmerón, I.; Plakas, K.; Sirés, I.; Oller, I.; Maldonado, M.I.; Karabelas, A.J.; Malato, S. Appl. Catal. B: Environ. 2019, 242, 327.

Acknowledgements Financial support from project PID2019-109291RB-I00 (AEI, Spain), as well as the contribution of all students and collaborators of LEMMA group are sincerely acknowledged.

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Combination of spectroelectrochemistry techniques.

Alvaro Colinaa, Juan V. Perales-Rondona,b, Sheila Hernandeza, Martin Perez-Estebaneza, Aranzazu Herasa

a Universidad de Burgos, Department of Chemistry, Plaza Misael Bañuelos s/n, E-09001, Burgos, Spain b Universidad de Alcalá de Henares, Department of Chemistry, Alcalá de Henares, Spain. [email protected]

Spectroelectrochemistry (SEC) is a set of techniques that combines electrochemistry with at least a spectroscopy technique1. This combination of analytical techniques provides very valuable information related to the interfacial processes occurring at the working electrode. Electrochemistry is very powerful to control chemical reactions, provoking the transformation of the analyte and providing the current/potential signal involved in the process when a potential/current is applied. In SEC, the electrochemical information is complemented by the evolution of the spectra that are concomitantly obtained during the electrochemical measurement. Depending on the nature of the spectroscopic technique, electronic or vibrational information can be extracted from the analysis of the optical response. The technical developments in recent years has allowed obtaining SEC measurements in a much easier way, and moreover, the combination of more than one spectroscopic measurement can be performed with relative simplicity. Bidimensional SEC2 can be considered the first combination of SEC techniques. In its early stage, this technique had some technical issues regarding the instrumental developments. However, the devices have been highly improved3 and, nowadays, this type of experiments can be carried out in any laboratory. Recently, a modification of this setup allowed us to obtain Raman and UV/Vis absorption measurements in parallel arrangement simultaneously4. In this communication, the new combination of SEC techniques developed in our group are shown. Raman has been combined with UV/Vis absorption measurements in normal arrangement. Also, photoluminescence and Raman measurements are obtained concomitantly. We have developed a dual Bidimensional SEC setup and a new thin-layer Bidimensional SEC cell. Finally, a combination of SEC with Scanning Electrochemical Microscopy is presented.

ACKNOWLEDGMENTS Authors acknowledge the financial support from Ministerio de Economía y Competitividad (Grants CTQ2017-83935-R-AEI/FEDER, UE), Ministerio de Ciencia, Innovación y Universidades (RED2018-102412-T) and Junta de Castilla y León (Grant BU297P18). S.H. thanks its predoctoral contract funded by Junta de Castilla y León. M. P-E. thanks its contract funded by Junta de Castilla y León, the European Social Fund and the Youth Employment Initiative.

REFERENCES (1) Garoz‐Ruiz, J.; Perales‐Rondon, J. V.; Heras, A.; Colina, A. Electroanalysis 2019, 31, 1254. (2) López-Palacios, J.; Colina, A.; Heras, A.; Ruiz, V.; Fuente, L. Anal. Chem. 2001, 73, 2883. (3) Garoz-Ruiz, J.; Heras, A.; Palmero, S.; Colina, A. Anal. Chem. 2015, 87, 6233. (4) Ibañez, D.; Garoz-Ruiz, J.; Heras, A.; Colina, A. Anal. Chem. 2016, 88, 8210.

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Electrochemical water treatment technologies: Steps towards higher technology readiness level

Sergi Garcia-Seguraa

a Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment. School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, 85287-3005, United States [email protected]

Electrocatalytic and electrochemically driven processes have shown promising advances for environmental remediation. Electrochemical advanced oxidation processes (EAOP) demonstrated great capabilities on the abatement of persistent organic pollutants. Techno- economic analyses suggest that electrochemical processes are cost-competitive strategies compared against existing technologies (e.g., activated carbon block (CB)) to remove anthropogenic groundwater contaminants such as atrazine, nitrate or other ubiquitous pollutants (e.g., nitrate). However, still there is a long path to follow before translating these emerging technologies to commercialization.

This work identifies and discusses research needs and engineering advances to move electrochemically-driven water treatment to higher technology readiness levels (TRL). Recent advances of our research group evaluating technology competitiveness and performance for nitrate and organics remediation from water sources will be presented. The presentation will also bring in one of the lesser explored aspects in the field of environmental electrochemistry: aging and fouling of electrodes. Finally, we will discuss briefly about techno-economic aspects that must be considered and how cost-learning curves may contribute to technology translation.

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Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

Redox Flow Technologies: Definition and Illustrations

Mathieu Etienne

CNRS and Université de Lorraine, LCPME, 54000 Nancy [email protected]

Redox flow technologies sometimes refer to redox flow batteries in the current scientific literature. In this communication, we wish to discuss the definition of Redox Flow Technologies and to illustrate that this definition can be associated to a wider range of applications, ranging from energy storage (of course!), to electrosynthesis and water remediation. The term can also apply to a wide range of hybridized flow technologies. Some examples will be taken from our current research.

This work has been supported by the European Union under HIGREEW, Affordable High- performance Green Redox Flow batteries (Grant Agreement no. 875613).

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______Posters ______

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P01-Effect of using different epoxi blends on the stability and performance of electrodes in a FCPEM.

M.A. Gómez, A.J. Navarro and J.J. López Cascales Universidad Politécnica de Cartagena, Dep. Ing. Química y Ambiental Campus de Alfonso XIII, Aulario C, 30203, Cartagena Murcia, Spain. email: [email protected]

During the last decades, hydrogen has been considered as a real alternative to fossil fuels. An advantage of hydrogen in comparison with other fuels, is related to the fact that when hydrogen is used in a fuel cell, electrical current is produced in a clean way, obtaining only water and heat as waste of the process, if hydrogen is generated by electrolysis using renewable resources.

In this context, fuel cell proton exchange membrane (FCPEM) is attracting a great interest in comparison with the other fuel cells due to the fact that they use a solid electrolyte, they work a low temperatures, they provide high densities of electrical current and they are very stable against CO2 and mechanical vibrations, which made them suitable for its employment in vehicles. However, one of the main challenges of this type of fuel cells are facing for their implementation in a wide number of applications, is related with the duration of their average life. One of the main facts that limit the stability and duration of the fuel cells, is related with the stability of the electrodes, as a consequence of the release of the catalyst with the working time of the fuel cell.

In this work, we present the preliminary results of an open cathode fuel cell, in which epoxy blending have been used in the preparation of their electrodes. In this regard, we show as the use of epoxi in the electrode preparation, at small quantities, in combination with nafion as binding agent during the electrodes preparation, and using the electrospray technique for its deposition, an improvement in the stability of the MEA (Membrane Electrode Assemble) and an extension the mean life of the fuel cells is measured.

Thus, in this work we present different studies that support the above assessment based in different studies such as hydrophobicity, thermal and electrical conductivity and polarization curves, obtained in different performance regimes and temperatures.

References [1]Spiegel, C.S. “Designing and Building Fuel Cells”, The McGraw-Hill, 2007. [2]Rebecca L. Busby, Hydrogen and fuel cells. A comprehensive Guide. Pennwell Corporation 2005. [3] Lopez Cascales, J.J.;Ibañez Molina, J.;Sánchez Vera, J. and Vivo Vivo, P.M. Renew. Energy 2015, 77, 79-85. [4]S. Lister and C. Mclean “PEM fuel electrodes”, J. Power Sources 130, 61-76, 2004.

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P02-Electrochemical detection of mercaptans in wine using gold nanoparticle-modified carbon electrodes

M. Asunción Alonso-Lomilloa, Sheila López-Gila, F. Javier del Campo Garcíab, Olga Domínguez-Renedoa

a Analytical Chemistry Department, Faculty of Sciences, University of Burgos, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain. b IKERBASQUE, Basque Foundation for Science, 48009, Bilbao, Spain. [email protected]

The organoleptic virtues of wine can be damaged by the presence of compounds produced during fermentation or aging, such as mercaptans. The quick and accurate identification of off-odors is vital to both winemaker and wine merchant, as early corrective action before the flaw becomes serious or irreversible avoids the ensuing economic losses1,2.

This work presents an environmentally friendly electrochemical sensor for the easy detection of mercaptans in wine samples, using glassy carbon and screen-printed carbon electrodes. The procedure was based on the electrochemical reduction of mercaptans3,4. The modification of the carbon working electrodes with gold nanoparticles increased the sensitivity and selectivity of the procedures, considering the strong covalent bond that forms readily between sulfur and gold atoms.

Ethanethiol reduction has been shown to depend both on pH and on adsorption time since the electrode is immersed in the solution until the voltammogram is recorded. The highest current has been recorded in a supporting electrolyte solution at pH 4.2 with an adsorption time of 10 min in the case of gold nanoparticle modified glassy carbon electrodes and pH 3 and 90 s for gold nanoparticle screen-printed carbon electrodes. The developed procedures reach a reproducibility of 7.9 % (n=7), based on the slopes associated with different calibration curves registered in the concentration range from 7.7 to 36.6 µg/L when using gold nanoparticle modified glassy carbon electrodes and 7.2 % (n = 5) in the case of gold nanoparticle modified screen-printed carbon electrodes (concentration range, from 1.6 to 10.9 µg/L). The sensors have successfully been applied to the detection of ethanethiol, representing mercaptans, in white and red wines.

Authors would like to acknowledge funding from Junta de Castilla y León and Spanish Ministry of Science, Innovation and Universities through project grants Bu08G19 and TEC2013-48506-C1 (DADDi2).

References (1) Flanzy, C. Enología: Fundamentos Científicos y Tecnológicos, Mundi Prensa, Madrid, 2003. (2) Jackson, R. S. Wine Science: Principles and Applications. Food science and technology. Academic Press, London 2014. (3) Guarda, A.; Maciel, J. V.; Wiethan, B. A.; Schneider, A.; do Nascimento, P. C.; Dias, D. Food Anal. Methods 2017, 10 (3), 837–844. (4) Serafim, D. M.; Stradiotto, N. R. Fuel 2008, 87 (7), 1007–1013.

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P03- Oxygen presence and corrosion rate of reinforcement on mortar specimens

a b Carmen Andrade and Juan Antonio Morales

a International Center for Numerical Methods in Engineering (CIMNE).UPC-Spain b Institute of Construction Sciences ”Eduardo Torroja”- CSIC-Spain (during the experiments) [email protected]

Abstract

The steel embedded in concrete or mortar passivates due to the high alkalinity provided by the cement hydration products based in saturated calcium hydroxide. The steel may corrode in the high pH values decrease due to the action of the atmospheric CO2 or by the presence of chlorides. When corrosion starts its rate depends mainly on the amount of moisture in the concrete pores and if the material is saturated it depends mainly on its porosity. Both porosity and water saturation degree are accounted for by the concrete electrical resistivity, property which controls the corrosion rate evolution (1). Although it is known that oxygen is not needed for the progression of the corrosion due the acidity produced by the corrosion provides protons for the cathodic reaction, there are authors questioning that principle. In present work it is explored the effect of a decrease of oxygen in the environment in that progress and whether there might be any relation between oxygen content and corrosion rate. In a previous work (2), steels immersed in alkaline solutions reproducing the concrete pore solution with different chloride concentrations where de-areated and the bars potentiostatically polarized confirming that in very low content solutions, strong corrosion may develop is there are sufficient chlorides, and the potential is in certain range. Present work made tests in mortar specimens with embedded steel bars restricting the access of oxygen to the embedded reinforcement by using a glove chamber. In its interior with a permanent nitrogen atmosphere, specimens were fabricated adding chlorides to the mortar mix and with previous de-areation of the mixing water by flowing nitrogen through it during certain time. For comparative purposes, reference mortar specimens were made by having them in the laboratory (dry) ambient or completely immersed in water, which supposes two different elvels of oxygen access to the bars. The results show that the oxygen is not a controlling parameter of the corrosion as the corrosion develops and progresses as soon as chlorides are present in the mix irrespective whether they are in the nitrogen filled glove chamber or out of it..

References (1) Andrade C., Fullea J., Alonso C., - MESINA- RILEM Proc. No. 18. Ed. C. Andrade, C. Alonso, J. Fullea, J. Polimon and J. Rodriguez. Rilem Publications S.A.R.L. (2000) 157-166. (2) Andrade C,, Fullea J., Toro L., Martinez I., Rebolledo N. – International Conference NUCPERF 2012- Cadarache- France

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P04-Magnetron sputtered NiO thin films for sodium ion battery electrode

Mario Aparicio,a Jadra Mosa,a Francisco José García-García,b and Agustín R. González- Elipeb

a Instituto de Cerámica y Vidrio (CSIC), Kelsen 5, Madrid, Spain b Instituto de Ciencia de Materiales de Sevilla (CSIC-Universidad de Sevilla), Avda. Américo Vespucio 49, Sevilla, Spain [email protected]

NiO thin film electrodes were successfully prepared by magnetron sputtering (MS) deposition under an oblique angle configuration (OAD). Intercalation of Na ions in the nickel oxide layers has been studied using electrochemical techniques (cyclic voltammetry, galvanostatic discharge-charge cycles and electrochemical impedance spectroscopy). Sample characterization before and after sodium intercalation has been carried out by SEM, micro- Raman, XPS, RBS and XRD measurements. The porous structure of the films is confirmed by electron microscopy evaluation. The increasing of the cycle’s number leads to a continuous 0 reduction of the discharge capacities due to some amount of Ni and Na2O produced during the discharge process remains in the electrode and does not participate in the charge process. Sodium half cells have shown a discharge capacity of 465 mAh g-1 after 16 cycles at 400 mA g-1 between 0.01 and 3.00 V (vs. Na+/Na).

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P05-Carbon-free cathode materials for metal-air batteries based on Ti compounds

Mario Aparicio,a Jadra Mosa,a Sho Ishiyama,b Nataly C. Rosero-Navarro,c Akira Miura,c and Kiyoharu Tadanagac

a Instituto de Cerámica y Vidrio (CSIC), Kelsen 5, Madrid, Spain b Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-8628, Japan c Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Sapporo 060- 8628, Japan [email protected]

TiOxNy powders were synthesized by sol-gel using titanium (IV) isopropoxide. Interconnected porosity was incorporated through phase separation of hydrophilic and hydrophobic blocks, and elimination of organic components with a thermal treatment. Partial substitution of oxygen by nitrogen was accomplished using thermal treatment in NH3 atmosphere and incorporation of urea during the synthesis procedure. Powder characterization includes surface area (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV). The results show a high surface area around 200 m2/g and a combination of titanium oxides, nitrides and oxinitrides.

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P06-Electrochemical detection of fentanyl using screen-printed carbon electrodes for seized drugs of abuse and forensic applications

a b a a a Colby E. Ott, Hugo Cunha-Silva, Sara L. Kuberski, Kourtney A. Dalzell, Joseph Cox , M. Julia b a Arcos-Martínez, and Luis E. Arroyo-Mora

a Department of Forensic and Investigative Science, West Virginia University, 1600 University Avenue, WV 26505, United States b Departamento de Química, Universidad de Burgos, Pza. Misael Bañuelos, Burgos, Spain [email protected]

Enhanced and rapid screening techniques for seized drug substances are needed in the forensic community to increase the reliability of results, improve case management, and provide an on-site analysis approach. As the United States and other countries face the opioid epidemic and COVID- 19 restrictions, fentanyl continues to be a prolific and important drug of interest, requiring novel and fast detection approaches. Fentanyl is commonly encountered in pure and cut forms with other drugs and diluents, representing a problematic sample for current drug color tests. Fentanyl is an opioid receptor agonist with a potency of approximately 100X that of morphine and commonly results in overdose deaths (1). The fentanyl molecule presents an electroactive nitrogen within the piperidine ring. Of interest to this study was the electrochemical oxidation process of fentanyl for detection of the analyte both alone and in the presence of potentially interfering compounds for situations related to seized drug analysis. This work demonstrates the electro-oxidative behavior of fentanyl, resulting in two anodic peaks at 0.75 V and 0.88 V versus Ag/AgCl pseudo reference electrode. Analysis was performed on homemade screen-printed carbon electrodes. The linear dynamic range was between 0.076 μg/mL and 6.9 μg/mL, with a limit of detection of 0.037 μg/mL. Interference studies were conducted on commonly encountered diluents such as cocaine, methamphetamine, quinine, caffeine, and acetaminophen. The accuracy and suitability of the method was explored through the assessment of 11 simulated seized drug samples (2). Proof of concept for detection capabilities in the oral fluid matrix was explored for future use with driving under the influence of drugs cases.

References (1) Vardanyan, R. S.; Hruby, V. J. Futur. Med Chem. 2014, 6(4), 385-412. (2) Ott, C.E.; Cunha-Silver, H.; Kuberski, S. L.; Cox, J. A.; Arcos-Martínez, M. J.; Arroyo-Mora, L. E. J. Electroanal. Chem. 2020, 873, 1-9.

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P07- Spectroelectrochemical screening of drugs of abuse for time- resolved electrochemical and SERS detection in forensic investigations

Colby E. Ott,a Jerson González-Hernández,b,c Sara L. Kuberski,a Kourtney A. Dalzell,a Travon Cooman,a Ana L. Alvarado-Gámez,b Roberto Urcuyo,b,c,d M. Julia Arcos- e e e a Martínez, Aranzazu Heras, Alvaro Colina, and Luis E. Arroyo-Mora.

a Department of Forensic and Investigative Science, West Virginia University, 1600 University Avenue, WV 26505, United States b Centro de Investigación en Electroquímica y Energía Química (CELEQ), Universidad de Costa Rica, San José, Costa Rica c Escuela de Química, Universidad de Costa Rica, San José, Costa Rica d Centro de Investigación en Ciencias e Ingeniería de Materiales (CICIMA), Universidad de Costa Rica, San José, Costa Rica e Departamento de Química, Universidad de Burgos, Pza. Misael Bañuelos s/n, Burgos, Spain [email protected]

Screening for commonly prescribed drugs and schedule drugs at crime scenes or within the field suffers from subjective results, lack of sensitivity, and selectivity. It is mainly affected by the constant influx of novel psychoactive substances [1]. As such, efficient, rapid, and reliable methodologies are needed to ensure the timely administration of justice and inform case management activities. The combination of electrochemical and spectroscopic information presents a feasible and cost-effective solution for identifying legal and illicit substances in clinical and forensic samples using portable instrumentation.

Electrochemistry and Raman spectroscopy are methods capable of distinguishing between many different analytes with fast, simple, and portable techniques. Electrochemistry was used as the first stage of detection in the sequence providing oxidative and reductive information. Second, the in-situ generation of a surface-enhanced Raman spectroscopy (SERS) substrate was achieved using voltammetric pretreatment to strengthen the Raman signals of interest to identify analytes. SEM-EDS and AFM were used to characterize the surface of the electrodes.

This orthogonal approach is used for the analysis of analytes and diluent substances within a panel comprised of 15 of the top 25 most encountered drugs according to the National Institute on Drug Abuse and 15 common diluents. Screen-printed gold and silver electrodes were utilized for EC-SERS along with screen-printed carbon electrodes for voltammetric detection. Characterization of the analytes individually using these orthogonal techniques was accomplished. Then simulated seized drug samples comprised of mixtures at various ratios (i.e., 1:4, 1:7, etc.) were analyzed for identification purposes. Lastly, the applicability of this method for clinical analysis was evaluated by measuring samples in urine and oral fluid. Some of the analytes of interest include fentanyl, mitragynine, mephedrone, 4- methylethcathinone, buprenorphine, naltrexone, and heroin.

References (1) Vardanyan, R. S.; Hruby, V. J. Futur. Med Chem. 2014, 6(4), 385-412.

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P08-Synthesis of ZnO nanostructures for hydrogen production

P. Batista-Grau a, R. Sánchez-Tovar a,b, R. M. Fernández-Domene a,b, P. J. Navarro-Gazquez a J. García-Antón a

a Ingeniería Electroquímica y Corrosión (IEC), Instituto Universitario de Seguridad Industrial, Radiofísica y Medioambiental (ISIRYM), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain. b Departamento de Ingeniería Química, Universitat de València, Av de les Universitats, s/n, 46100 Burjassot, Spain. [email protected]

Zinc oxide (ZnO) is an n-type semiconductor with numerous applications in photocatalysis due to its abundance, non-toxicity, versatility and photoelectrical properties. In the present study, ZnO nanostructures were synthesized by anodization method in NaHCO3 aqueous electrolyte under different controlled hydrodynamic conditions (from 0 to 5000 rpm) followed by thermal annealing. Morphology, crystallinity and vibrational properties of the samples were studied by means of Field Emission Scanning Electron Microscope (FE- SEM) and Confocal Laser-Raman Spectroscopy. Finally, photoelectrochemical water splitting measurements using ZnO nanostructures as photoanodes were performed. According to the results, the synthesized ZnO nanostructures presented high photocurrent density response during water splitting experiments in aqueous Na2S/Na2SO3 electrolyte as it is shown in Figure 1, especially the sample anodized at 5000 rpm. Additionally, rotation speeds higher than 3000 rpm during anodization improved the surface homogeneity of the sample and decreased dark current density values during water splitting test.

Figure 1. Current density under on/off simulated sunlight as a function of the applied potential.

Acknowledgements Authors would like to express their gratitude to the Generalitat Valenciana and to the European Social Fund for their financial support within the subvention GJIDI/2018/A/067. Authors thank AEI (PID2019-105844RB-I00/ AEI/10.13039/501100011033) for the financial support and, as well, to E3TECH under project CTQ2017-90659-REDT (MINECO, Spain). Authors also thank to project co-funded by FEDER operational programme 2014-2020 of Comunitat Valenciana (IDIFEDER/18/044). P.J. Navarro-Gázquez thanks the “Ministerio de Ciencia e Innovación” for the award of a Youth Guarantee Aid (PEJ2018-003596-A-AR).

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P09-Electrochemical treatment of Naproxen with surface modified pitch- derived open-pore graphite foam anodes

F. Casesa, J. Fernándeza, J. Bonastrea , J.M. Molinab

aDepartamento de Ingeniería Textil y Papelera, Escuela Politécnica Superior de Alcoy, Universitat Politècnica de València, Plaza Ferrándiz y Carbonell, s/n, 03801 Alcoy, Spain. bDepartamento de Química Inorgánica de la Universidad de Alicante e Instituto Universitario de Materiales de Alicante, University of Alicante, Ap 99, E-03080 Alicante, Spain. [email protected]

The electrochemical behavior of a pitch-derived open-pore graphite foam (CF) was successfully improved by coating its surface with reduced graphene oxide (RGO) and platinum (Pt) nanoparticles. The RGO was synthesized using cyclic voltammetry (CV). For the electrodeposition of platinum nanoparticles, an alternate current method based on electrochemical impedance spectroscopy (EIS) was used. The electrochemical activity of the electrodes CF, CF/RGO, CF/Pt, and CF/RGOPt was compared using CV, EIS, and scanning electrochemical microscopy (SECM). The morphology and chemical composition of the electrode surfaces were examined using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX), respectively. Smaller Pt nanoparticles and a higher level of coating were observed on the surface of CF/RGOPt. The applicability of CF, CF/Pt, and CF/RGOPt as anodes in the remediation of wastewater was tested by means of the oxidation of naproxen (which is considered an emerging pollutant). High performance liquid chromatography (HPLC), UV-visible and Fourier transform infrared (FTIR) spectroscopies were used to monitor the naproxen oxidation. High oxidation percentages (90%) were obtained with the CF/RGOPt electrode after a loaded charge of about 1.70x10-4 Ah L-1. A severe destruction of the aromatic structure without the generation of new aromatic species or other complex structures is inferred from the FTIR and UV-visible spectra. In addition, a change in the kinetics, as a consequence of the nature of the electrode material, from a pseudo-zero order for CF and CF/Pt electrodes to a pseudo-first order for CF/RGOPt electrodes was observed.

Figure. (a) Percentage of NPX oxidation versus loaded charge. From (b) to (d) kinetics for (b) CF, (c) CF/Pt, and (d) CF/RGOPt.

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P10-Influence of the Medium on Electron Transfer of Ferri/Ferro-cyanide Across Mercapto-hepta(ethylene glycol) Self-Assembled Monolayer on Gold

Miriam Chávez, Guadalupe Sánchez, Rafael Madueño, José M. Sevilla, Manuel Blázquez, Teresa Pineda

Departamento de Química Física y T. A., Instituto de Química Fina y Nanoquímica, Universidad de Córdoba, Campus Rabanales, Ed. Marie Curie 2ª P, 14014 Córdoba, España [email protected]

Self-assembled monolayers (SAMs) of oligo- or polyethylene glycol (EGn, where n is the polymerization degree) have been an important issue in biomedical research for many years. The inhibition of nonspecific protein and cell adhesion make these EGn-SAMs to be commonly used to improve biocompatibility in some applications such as biosensors.1 Accordingly, the study of their tendency to modify the rate of heterogeneous electron transfer of redox couples seems important,2 as it can inform about the chains conformation and interfacial properties.

Buess-Hermann et al. have evaluated the behavior of ferricyanide redox probe in the presence of a EG7-SAM, focusing on the hydration properties of both the electroactive anions and the monolayer.3, 4 Here, we propose that not only water molecules are responsible for completely suppress the electron transfer of the system. On the one hand, we have evaluated the effect of the solvent nature in the solution used for the formation of the SAMs. The preparation of EG7- SAMs on gold 2D surfaces from tetrahydrofuran, ethanol, ethanol/water mixture and phosphate buffer solutions has been performed with some significant differences in their behavior. On the other hand, the peculiar behavior of this redox probe is discussed in terms of the supporting electrolyte, which should also be decisive when the electron transfer is completely suppressed in the presence of the SAM.

Cyclic voltammetry (CV) and Electrochemical Impedance spectroscopy (EIS) techniques are used to evaluate these effects. Also, contact angle measurement demonstrate that the quality of SAMs depends critically on the choice of solvents.

Acknowledgements: We thank the Ministerio de Ciencia e Innovación (Project RED2018-102412-T Network of Excellence Electrochemical Sensors and Biosensors), Junta de Andalucía and Universidad de Cordoba (UCO-FEDER-2018: ref. 1265074-2B and Plan Propio, SUBMOD. 1.2. P.P. 2019). M.C. thanks the Ministerio de Cultura y Deporte (Ayuda FPU17/03873.) for financial support of this work.

References.

1. Hotchen, C. E.; Maybury, I. J.; Nelson, G. W.; Foord, J. S.; Holdway, P.; Marken, F., Phys. Chem. Chem. Phys. 2015, 17 (17), 11260-11268. 2. Chávez, M.; Sánchez-Obrero, G.; Madueño, R.; Sevilla, J. M.; Blázquez, M.; Pineda, T., J. Electroanal. Chem. 2021, 880, 114892. 3. Doneux, T.; de Ghellinck, A.; Triffaux, E.; Brouette, N.; Sferrazza, M.; Buess-Herman, C., J. Phys. Chem. C 2016, 120 (29), 15915-15922. 4. Doneux, T.; Cherif, L. Y.; Buess-Herman, C., Electrochim. Acta 2016, 219, 412-417.

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P11-Effect of ionic strength on the molecular organization of polyethylene glycol (PEG) SAMs on gold surfaces

Miriam Chávez, Guadalupe Sánchez, Rafael Madueño, José M. Sevilla, Manuel Blázquez, Teresa Pineda

Departamento de Química Física y T. A., Instituto de Química Fina y Nanoquímica, Universidad de Córdoba, Campus Rabanales, 14014 Córdoba, España [email protected]

The development of multifunctional hybrid materials of use in biosensors or theragnostic applications is a topic of interest for the advance of Nanomedicine. 2-D and 3-D gold surfaces covered with oligo- or poly-ethylene glycol (EGn) films are an attractive option, due to its antifouling properties, in particular, the protection against unspecific adsorption of proteins.1

One of the most important parameters determining the interaction of nanomaterials and planar substrates with proteins is the grafting density and chain conformation of the EGn used to protect the surface. Under low grafting densities, there are not lateral constraints, and the polymeric films usually adopt a swollen conformation, behaving like a free polymer in solution and the Flory radius describes the size of the random coil that is formed by such a polymer in solution. This kind of structure is known as “mushroom”. On the other hand, when the grafting density is high, the polymer chains are forced into a stretched (or “brush”) conformation where the contacts between neighboring chains are minimized, and the polymer-solvent contacts are maximized. Therefore, it is essential to establish the best conditions for performing the formation of the polymeric film. Vaknin et al. 2,3 have evaluated the influence of different salt concentrations. The addition of ions to the solution diminishes the solubility of the polymers and could provoke the self-assembly of the EGn on the surface and its phase separation.

In this work we have evaluated the influence of different solvents and saline concentration on the organization degree within the layers formed with EGn-SH of different molecular weight (n = 3 to 136) on gold substrates.4 These studies have been asserted by using cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy and contact angle measurements.

Acknowledgements: We thank the Ministerio de Ciencia e Innovación (Project RED2018-102412-T Network of Excellence Electrochemical Sensors and Biosensors), Junta de Andalucía and Universidad de Cordoba (UCO-FEDER-2018: ref. 1265074-2B and Plan Propio, SUBMOD. 1.2. P.P. 2019). M.C. thanks the Ministerio de Cultura y Deporte (Ayuda FPU17/03873.) for financial support of this work.

References (1) Cai, R.; Ren, J.; Ji, Y.; Wang, Y.; Liu, Y.; Chen, Z.; Farhadi Sabet, Z.; Wu, X.; Lynch, I.; Chen, C. ACS Appl. Mater. Interfaces 2020, 12 (2), 1997-2008. (2) Nayak, S.; Fieg, M.; Wang, W. J.; Bu, W.; Mallapragada, S.; Vaknin, D., Langmuir 2019, 35 (6), 2251-2260. (3) (3) Wang, W.; Kim, H. J.; Bu, W.; Mallapragada, S.; Vaknin, D., Langmuir 2020, 36 (1), 311-317. (4) Chávez, M.; Sánchez-Obrero, G.; Madueño, R.; Sevilla, J. M.; Blázquez, M.; Pineda, T., J. Electroanal. Chem. 2021, 880, 114892.

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P12-Composite materials from metal carbides and ionic liquids for hydrogen evolution reaction

Sergio Díaz-Coello,a Gonzalo García,a Benito Anulab and Elena Pastora

a Instituto de Materiales y Nanotecnología, Departamento de Química, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez s/n, 38200, La Laguna, Spain b Alisios Soluciones Energéticas S.L.L., C/ Camino del Hierro 13, 38009 Santa Cruz de Tenerife, Spain [email protected]

An option to reduce the price of high-purity H2 production is the development of new non-noble electrocatalysts with great activity towards water electrolysis reactions. Thus, transition metal carbides (TMCs) have appeared as a promising alternative to platinum catalysts since they present a Pt-like electronic structure close to the Fermi level (1). On the other hand, ionic liquids (ILs) have recently risen some interest in electrochemical applications due to their good electrical and mechanical properties (2). In this work different composite materials have been achieved by mixing several TMCs with N-octylpyridinium hexafluorophosphate (OPy). Physicochemical characterization has been made by electronic microscopy and Raman spectroscopy. The catalytic activity towards hydrogen evolution reaction (HER) has been evaluated by differential electrochemical mass spectrometry (DEMS). Results show that the presence of OPy in the composite material determines the mean particle size and the detected Raman vibrations (mostly oxides). Moreover, the change of these parameters alters the catalytic activity of the starting material. It seems that these effects can be related with the increase in the stability of surface oxides for the TMCs from group VI (W and Mo) and the decrease for VC and TiC, produced by the addition of OPy (see Table 1).

Table 1. Compilation of particle sizes and overpotential (η) determined by DEMS in 0.1 M NaOH at 1 mVꞏs-1 for all materials studied in the present work. Particle size without Particle size with η without η with Sample OPy / nm OPy / nm OPy / mV OPy / mV

W2C 662 544 275 190 WC 259 242 110 100 Mo2C 484 420 185 145 VC 334 357 260 360 TiC 31 35 334 334

References (1) Liu, Y.; Kelly, T.G., Mustain, W.E. ACS Catalysis 2013, 3, 1184. (2) Appetecchi, G.B., Kim, G.T., Montanino, M., Alessandrini, F., Passerini, S. Journal of Power Sources 2011, 196, 6703.

Acknowledgement: this work has been founded by the MICINN thought the project ENE2017- 83976-C2-2-R (co-founded with FEDER) and the PCI2020-112249. G.G. acknowledges the program Viera y Clavijo (ACIISI and ULL) and S.D.C. acknowledges the ACISII for financing their post- and pre- Ph.D grants, respectively.

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P13-Aryl diazonium electrografting based strategies for the development of voltammetric sensors

José Manuel Díaz-Cruza,b, Núria Serranoa,b, Clara Pérez-Ràfolsa, Miguel Rosala, Cristina Ariñoa,b, Miquel Estebana,b

a Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain. b Water Research Institute (IdRA), University of Barcelona. [email protected]

The determination of trace heavy metals presents obvious concerns for both human health and environment. In this sense, stripping techniques and, in particular, anodic stripping voltammetry (ASV), are especially suitable due to their intrinsic features i.e. excellent detection limits, high reproducibility and sensitivity, and relatively low cost. However, it is worth noting that the performance of voltammetry is strongly influenced by the working electrode material1. Particularly, chemically modified electrodes present the advantage that sensitivity and selectivity can be regulated by the incorporation of a convenient functional group onto the electrode surface. In this respect, the immobilization based on aryl diazonium salt electrografting has proven its benefits in the development of sensors for metal ion determination2. Regarding modifiers, peptides are effective ligands for a great variety of metal ions. Their ability to bind metals is a consequence of the great number of donor atoms not only in their peptide backbone but also in their aminoacid side chains. In this work, two different modification strategies by means of aryl diazonium salt electrografting were compared for the development of voltammetric sensors. In this sense, L-cysteine was immobilized onto a screen- printed carbon-based electrode surface through either its –NH2 or its –COOH group and the performance of the resulting modified sensors was tested for the simultaneous determination of Pb(II) and Cd(II) as a model metal ion system by ASV3.

(1) Ariño, C.; Serrano, N.; Díaz-Cruz, J.M.; Esteban, M. Anal. Chim. Acta 2017, 990, 11-53. (2) Gooding, J.J.; Hibbert, D.B.; Yang, W.; Sensors 2001, 1, 75-90. (3) Pérez-Rafols, C.; Rosal, M.; Serrano N.; Ariño, C.; Esteban, M.; Díaz-Cruz, J.M. Electrochim. Acta 2019, 319, 878-884.

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P14-Molecularly imprinted polypyrrole based electrochemical sensor for selective determination of ethanethiol

Olga Domínguez-Renedoa and M. Asunción Alonso-Lomilloa

a Analytical Chemistry Department, Faculty of Sciences, University of Burgos, Pza. Misael Bañuelos s/n, 09001, Burgos, Spain [email protected]

Wine contains a significant amount of volatile sulfur compounds that can significantly affect its flavor and aroma. Among these compounds are mercaptans, such as ethanethiol, associated with the appearance of unpleasant odors in some wines that resemble that of rotten onions1. Therefore, the determination of this compound is of extreme importance for wine producers to guarantee not only the quality of the wine, but also avoid serious economic problems derived from the rejection of the product by the consumer. Electrochemical techniques are characterized by high sensitivity and selectivity, a wide linear range and low-cost instrumentation. Moreover, electrochemical devices can be easily miniaturized for in situ applications. These advantages can be increased by modifying the working electrode with molecularly imprinted polymers (MIPs). MIPs have been successfully applied to the production of electrochemical sensors based on their selective biomimetic recognition of the analyte2. In addition, MIPs are characterized by important properties including high physical, chemical and mechanical stability and easy and low cost fabrication processes3. Moreover, the combination of MIP modified electrodes with nanostructures such as gold nanoparticles (AuNPs) is very promising for enlargement of active surface area, allowing a fast electron transfer between the redox analyte and the electrode surface. This work describes the development of an electrochemical sensor based on a MIP for sensitive and selective determination of ethanothiol in wine. The sensor has been built by the electrosynthesis of the MIP on a glassy carbon electrode surface using cyclic voltammetry. The electropolymerization has been performed in the presence of ethanothiol and pyrrole as template molecule and functional monomer, respectively. Important variables including, pH, molar ratios of template molecules to functional pyrrole monomers and the time needed to remove the template have been optimized, considering the differential pulse voltammetric response of ethanothiol. The developed sensor has been subsequently modified with AuNPs in order to increase its sensitivity, taking into account the special properties of nanoparticles.

Authors would like to acknowledge funding obtained by Junta de Castilla y León (BU018G19).

References

(1) López, R; Lapeña, A.C.; Cacho, J.; Ferreira, V. Journal of Chromatography A, 2007, 1143, 8. (2) Silva, B.V.M.; Rodriguez, B.A.G.; Sales, G.F.; Sotomayor, M.D.P.T. Dutra, R,F. Biosensors Bioelectronics, 2016, 77, 978. (3) Yang, L.; Yang, J.; Xu, B.; Zhao, F. Zeng, B. Talanta, 2016, 161, 413.

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P15-Electrochemistry of Isothiazolinonic Biocides: Oxidation and interaction with Cysteine

Mercedes Ruiz Montoyaa, Inmaculada Giráldezb, Emilio Moralesb, Rafael Estévez Britoc, José Miguel Rodríguez Melladoc

a Dpto. Ing. Química, Química Física y CC. Materiales, E.T.S. Ingeniería, b Dpto. Química “Prof. J.C. Vilchez Martín”, Facultad de CC. Exp., a & b Pro2TecS, Campus El Carmen, Universidad de Huelva, E-21071, Huelva, Spain c Dpto. de Química Física y Termodinámica Aplicada. IUIQFN, CeiA3, C. U. Rabanales, Edificio Marie Curie. Universidad de Córdoba, E-14014, Córdoba, Spain [email protected]

Biocides are substances used to destroy, inhibit, harmless or control harmful organisms. Currently, isothiazolinone derivatives, as methylisothiazolinone (MIT), chloromethylisothia- zolinone (CMIT) and 4,5-dichloro-2-octyl-4-isothiazolin-3-one (DCOIT), are widely used as biocides in many products as cosmetics, toiletries, hair and skin care products, reverse osmosis plants, adhesives1, biodiesel2, cooling water treatment, laundry detergents, paints, food packaging paper, etc. These biocides can cause allergic reactions in contact with the skin and even toxicity3. A glassy carbon electrode (GCE) has been used to study the oxidation of methylisothiazolinone (MIT), chloromethyl- isothiazolinone (CMIT) and 4,5-dichloro-2-octyl-4-isothia- MIT: R1=H, R2=H, R3=H zolin-3-one (DCOIT), by Cyclic (CV) and Differential Pulse CMIT: R1=H, R2=Cl, R3=H (DPV) Voltammetry. The conditions for electrooxidation were DCOIT: R1=Heptyl-, R2=Cl, R3=Cl optimized and the oxidation products were characterized by liquid-liquid extraction and GC- MS, confirming that the oxidation process involves two electrons and the opening of the isothiazolinonic ring. With respect to the interaction with cysteine, it was found that its oxidation peak decreased when the concentration of MIT and CMIT increased, therefore, thanks to the specificity of this interaction. This can be used to quantify the biocides present in a sample of usual cosmetics and household products4. B

A: Comparison of the DPV of MIT, CMIT B: DPV of 1 mM cysteine with mixtures of both MIT and and DCOIT. pH = 6.00 CMIT (ratio 1:3). Biocide concentrations are shown in the figure (1) M.C. Goodier, L.-Y. Zang, P.D. Siegel, E.M. Warshaw Dermatitis (2019), 30, 129. (2) G.V.S. Luz, B.A.S.M. Sousa, A.V. Guedes, C.C. Barreto, L.M. Brasil Molecules (2018), 23, 2698. (3) G.A. Kahrilas, J. Blotevogel, P.S. Stewart, T. Borch, Environ. Sci. Technol. (2015), 49, 16. (4) G. Alvarez-Rivera, T. Dagnac, M. Lores, C. Garcia-Jares, L. Sanchez-Prado, J.P. Lamas Jp, M. Llompart, J. Chromatogr., A (2012), 1270, 41.

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P16-An electrochemical method for the determination of Metformin

Mauricio Regalado Aguilar, Rafael Estévez Brito, Rafael Rodríguez Amaro, José Miguel Rodríguez Mellado Dpto. de Química Física y Termodinámica Aplicada. IUIQFN, CeiA3, C. U. Rabanales, Edificio Marie Curie. Universidad de Córdoba, E-14014, Córdoba, Spain [email protected]

Metformin (MF) (or the commercial preparation metformin hydrochloride) is one of the main medicines used in the treatment of type 2 diabetes1. MF works by decreasing and delaying the amount of glucose both absorbed from food at the intestinal level and produced by the liver. In addition, its promotes the effect of insulin in the body. However, it can present some problems, due to the lack of adequacy in its dose for each patient, which is adjusted according to blood glucose levels. Side effects due to inadequate doses can originate from stomach problems to lactic acidosis and hypoglycaemia. Therefore, it’s important to quickly and easily monitor the current dose of MF in the body and the excreted. This study is focused on developing an electrochemical method to determine the amount of MF in solution based on the decrease in the Cu Reduction-Oxidation signal2 in the presence of MF. This can be extended to real samples. A glassy carbon electrode (GCE) was used with Cyclic, Differential Pulse and Square Wave Voltammetry. Cu nanoparticles (CuNPs) have been immobilized on the surface of the GCE, but after a series of measurements, it was found that part of the CuNPs had come off the GCE surface (fig.1). Then, a polyaniline conducting polymer (PANI) was supported in the GCE, and the CuNPs were immobilized on it, but the polymer encapsulated the nanoparticles in a way that prevented their interaction with the MF (fig.2). For these reasons, the GCE with naked surface was used, Cu being in a solution (constant concentration) where MF was added, which provided the best results (fig. 3), thanks to the signal obtained by the Cu- MF complex. This complex was formed by applying a potential of 1.2 V for an optimized time (180 seconds). The working variables were optimized as close as possible to physiological conditions. Currently, concentrations of MF in solution of up to 5 M have been determined without any problem.

(1) R. A. DeFronzo, Anita M. Goodman, & Multicenter Metformin Study Group N Engl J Med (1995), 333, 541 (2) M. T. Moreno, R. Estévez Brito, J. M. Rodríguez Mellado J Electrochem Sci Tec. (2020) (under revision)

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P17-Rapid charge/discharge of PEDOT investigated by digital video electrochemistry (DVEC)

J. J. García-Jareño, M. Ferrer, J. Agrisuelas, E. Guillén and F. Vicente

Departament de Química Física, Universitat de València. C/ Dr. Moliner, 50, 46100, Burjassot, València, Spain [email protected]

Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most studied polymers with interesting charge/discharge and electrochromic properties1,2. PEDOT was electrodeposited in aqueous solution on indium thin oxide electrodes (ITO) and the rapid charge/discharge of PEDOT was investigated by fast cyclic voltammetry between 0.01 and 10 V s1. Fast RGB color changes were captured using a high-speed digital camera at 120 frames per second. Digital video electrochemistry correlates both the electrochemical and color data to investigate the fast processes taking place during cycles (Figure 1).

1 Figure 1. Digital video electrochemistry of a PEDOT film on ITO in 0.1 M LiClO4 at 10 V s

References (1) Meng, J.; Li, X.; Qin, M.; Pei, Y.; Yang, S.; Lan, Y.; Wang, R.; Chen, G. Effects of Pore Size of Reverse Opal Structured PEDOT Films on Their Electrochromic Performances. Organic Electronics 2017, 50, 16–24. (2) Agrisuelas, J.; Gabrielli, C.; García-Jareño, J. J.; Perrot, H.; Sel, O.; Vicente, F. Electrochemically Induced Free Solvent Transfer in Thin Poly(3,4-Ethylenedioxythiophene) Films. Electrochimica Acta 2015, 164, 21–30.

Acknowledgements This work was supported by MINECO-FEDER CTQ2015-71794-R and from Excellence Network E3TECH under project CTQ2017-90659-REDT (MINECO, Spain).

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P18-Understanding gas evolution from batteries via operando measurements

Nuria Garcia-Araez

University of Southampton, SO17 1BJ, Southampton, United Kingdom [email protected]

The formation of gases from lithium-ion batteries under abuse conditions is a serious safety issue that can cause the cell’s rupture and explosion [1], as well as the release of highly toxic gases [2]. In addition, the formation of gases under typical operation conditions is also very problematic, and a symptom of battery degradation that can be used to predict the battery lifetime [3].

Unfortunately, the techniques currently available for the study of gases from lithium batteries are very limited. For that reason, we have recently developed a new a new, simple and reliable cell design to monitor the operando pressure changes of Li-ion battery materials [3]. We have also successfully applied this new cell design to quantify the gases involved in the formation of the graphite SEI and to study the changes in the electrode’s volume induced by the electrochemical reactions of lithium insertion and extraction, thus demonstrating the very high sensitivity and reliability of our new cell design. In addition, further understanding of the mechanism of the reactions involving gas evolution has been obtained by coupling this cell design to a mass spectrometer for the quantitative characterisation of the gases evolved.

These new approaches for the study of gas evolution have also been applied for the development of lithium-oxygen batteries, which are not only a promising post lithium-ion battery candidate, but also an ideal model system to study the oxygen redox chemistry [4]. We have shown that it is possible to transform the mechanism of the oxygen redox reactions and efficiently bypass the formation of detrimental reaction intermediates (e.g. superoxide) via the incorporation of redox mediators [5,6], and in a recent study we have shown that unsuitable electrolytes, prone to degradation, can be made suitable via such transformation of the reaction mechanism [7].

These studies demonstrate that the fundamental understanding of the mechanism of battery reactions can be used to design suitable strategies to prevent degradation issues, such as the development of approaches designed to bypass the formation of species that act as degradation triggers.

References (1) D.P. Finegan et al. Adv. Sci. 2018, 5, 1700369 (2) N. P. Lebedeva et al. J. Electrochem. Soc., 2016, 163, A821. (3) N. Ryall et al. J. Electrochem. Soc., 2020, 167, 110511. (4) T. Liu et al. Chem. Rev., 2020, 120, 6558. (5) L. Yang et al. Chem. Commun., 2015, 51, 1705. (6) T. Liu et al. J. Am. Chem. Soc., 2018, 140, 1428. (7) J. P. Vivek et al. J. Phys. Chem. C, 2019, 123, 20241.

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P19-Predicting Pourbaix diagrams of flow-battery relevant anthraquinones from Density Functional Theory and COSMO-RS

Théophile Gaudin,a Véronique Nardello-Rataja and Jean-Marie Aubrya a Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181 – UCCS – Unité de Catalyse et Chimie du Solide, F-59000 Lille, France [email protected]

Redox flow batteries (RFBs) are secondary batteries in which the energy conversions are based on the reversible electrochemical reactions of two redox couples1. RFBs are ideally suited for relatively large stationary applications (capacities of 1 kWh to 10 MWh)2, among which is the highly relevant energy storage from intermittent sources such as solar or wind power3-5. Currently, most RFBs are based on Vanadium, allowing the use of water as a solvent. However, Vanadium is relatively rare and expensive6. Thus, in recent years, interest in RFBs based entirely or partly on more sustainable organic electrolytes has been raising7. For example, quinones, and in particular anthraquinones, are cheap and renewable. However, their limited solubility has pushed researchers to synthesize anthraquinones with solubilizing polar or ionic functional groups in order to reach useful energy storage densities, which can in turn can change their reduction potential at any pH, and therefore alter the energy storage capacity of the RFB, as can be seen on their potential-pH (aka Pourbaix) diagrams. In this contribution, we first present the performances of Density Functional Theory (DFT) combined with the COnductor- Like Screening MOdel for Realistic Solvation (COSMO-RS) to predict the pKa and reduction potential E0 of diverse quinones and quinols. Then, combining these predictions with the Nernst and Henderson-Hasselbalch equations, we demonstrate that Pourbaix diagrams of experimentally characterized anthraquinones (anthraquinone itself, anthraquinone 2,7- disulfonate, and anthraflavic acid) can be reproduced with reasonable accuracy. Based on this experimental validation, we discuss the impact of the position and nature of various side groups on anthraquinone on their Pourbaix diagrams to guide the future choice of posolyte and negolytes for RFBs. This work was financially supported by the Agence Nationale de Recherche (Grant number: ANR-19-CE05-0012). References (1) Zhang, H.; Li, X.; Zhang, J., Redox Flow Batteries: Fundamentals and Applications. CRC Press: Boca Raton, 2018. (2) Service, R. F., Advances in flow batteries promise cheap backup power. Science 2018, 362 (6414), 508. (3) Wang, W.; Sprenkle, V., Redox flow batteries go organic. Nature Chem. 2016, 8 (3), 204-206. (4) Yang, Z.; Zhang, J.; Kintner-Meyer, M. C. W.; Lu, X.; Choi, D.; Lemmon, J. P.; Liu, J., Electrochemical Energy Storage for Green Grid. Chem. Rev. 2011, 111 (5), 3577-3613. (5) Ding, C.; Zhang, H.; Li, X.; Liu, T.; Xing, F., Vanadium Flow Battery for Energy Storage: Prospects and Challenges. J. Phys. Chem. Lett. 2013, 4 (8), 1281-1294. (6) Zhang, M.; Moore, M.; Watson, J. S.; Zawodzinski, T. A.; Counce, R. M., Capital Cost Sensitivity Analysis of an All-Vanadium Redox-Flow Battery. J. Electrochem. Soc. 2012, 159 (8), A1183-A1188. (7) Lin, K.; Chen, Q.; Gerhardt, M. R.; Tong, L.; Kim, S. B.; Eisenach, L.; Valle, A. W.; Hardee, D.; Gordon, R. G.; Aziz, M. J.; Marshak, M. P., Alkaline quinone flow battery. Science 2015, 349 (6255), 1529-1532.

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P20-Spectroelectrochemistry of Nonunity Stoichiometry Electrode Reactions: A Theoretical Study

José María Gómez-Gil, Angela Molina, Eduardo Laborda, Juan García-Martínez Departamento de Química Física, Facultad de Química, Regional Campus of International Excellence“Campus Mare Nostrum”,Universidad de Murcia, 30100 Murcia, Spain [email protected]

Key electrochemical processes are reported to follow non-unity stoichiometries in a variety of scientific and technological fields1: energy storage and conversion (eg., halides in dye-sensitized solar cells, hydrogen production), environmental monitoring and assessment (eg., mercury complexes) and electrosynthesis (eg., dimerization of the electrode product), among others (see Scheme I).

Scheme I. Schematic and examples of electrochemical reactions with nonunity stoichiometry.

The full characterization of this kind of processes can be challenging considering the number of parameters to be determined, at least: the stoichiometric and diffusion coefficients of the redox species, the number of electrons transferred, and the formal potential of the couple O/R. Hence, as in other contexts2,3, the joint analysis of simultaneous electrochemical and spectroscopic measurements can be advantageous for comprehensive and sound studies. Attending to the above, a general theoretical treatment is developed in this work to model the spectroelectrochemical response at macroelectrodes of reversible electrode reactions with complex stoichiometry a:b (see Scheme I). The theory is applicable to any voltammetric perturbation and whatever the diffusion coefficient and bulk concentration of the redox species. Simple equations are derived for the current-potential response, surface concentrations and concentration profiles of the most common 2:1, 1:2, 3:1 and 1:3 cases. From the theoretical solutions obtained, the value of spectroelectrochemistry is assessed in the elucidation and quantitative characterization of the reaction stoichiometry. Thus, the voltabsortometric and chronoabsortometric responses are investigated both in normal and parallel modes, establishing suitable experimental approaches, diagnosis criteria and protocols for data analysis. Acknowledgements Fundación Séneca - Agencia de Ciencia y Tecnología Región de Murcia (19887/GERM/15). References (1) Gómez-Gil, J. M.; Laborda, E.; Molina, Anal. Chem. 2020, 92, 3728 and references therein. (2) Kaim, W.; Fiedler, J., Chem. Soc. Rev. 2009, 38, 3373. (3) Molina, A.; Laborda, E.; Gómez-Gil, J. M.; Martínez-Ortiz, F.; Compton, R. G., J. Electroanal. Chem. 2018, 819, 202.

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P21-Analysis by Synchrotron XRD and HAXPES of the Bi2O3 electrode Redox mechanism in KOH solution

Sebastián Lorca,a Florencio Santos,a José Abada, Antonio Urbinab, Juan Rubio-Zuazoc,d and Antonio J. Fernández Romeroa aGrupo de Materiales Avanzados para la Producción y Almacenamiento de Energía, Universidad Politécnica de Cartagena, Murcia, Spain bDepartamento de Electrónica, Tecnología de Computadoras y Proyectos, Universidad Politécnica de Cartagena, Plaza del Hospital 1, 30202, Cartagena, Spain cInstituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), C/Sor Juana Inés de la Cruz 3, 28049, Madrid, Spain dSpLine Spanish CRG Beamline at the ESRF, Grenoble, France

[email protected]

Bismuth oxide has been frequently studied as a material for rechargeable electrodes and it has been used as anode material in supercapacitors and more recently as negative electrode in Bi/Ni batteries1. Recently, our group has developed a new low cost and safe rechargeable battery of Zn/PVA-KOH/Bi2O3, which demonstrates a high number of charge/discharge cycles and good coulombic and energy efficiencies2. Different mechanisms have been proposed to explain the reduction/oxidation processes of the - Bi2O3 electrode. However, the entrance and exit of OH anions has been always considered as a fundamental step2, as indicates the following reaction:

Furthermore, in this communication, we analyze the influence of the concentration value of KOH solution on the behavior of the discharge and charge processes of a Bi2O3 electrode. Synchrotron XRD and HAXPES techniques have been used to characterize the Bi2O3 structure and the reduction state of bismuth species with the state of charge of the electrodes cycled in different KOH concentration solutions. Besides, cyclic voltammetry and chronoamperometric results will be presented.

Acknowledgements. The authors thank the financial support from Fundación Séneca (Región de Murcia, Spain; Ref: 20985/PI/18 and 19882-GERM-15), Spanish Agencia Estatal de Investigación (PID2019-104272RB-C55/AEI/10.13039/501100011033) and ESRF and ICMM-CSIC by provision of beam time at BM25 line (projects: 2010 6 0E 013 y 2021 60 E 030)

References [1] Zeng, Y.; Lin, Z.; Meng, Y.; Wang, Y.; Yu, M.; Lu, X.; Tong, Y., Advanced Materials 2016, 28, 9188-9195. https://doi.org/10.1002/adma.201603304. [2] S. Lorca, F. Santos, J. Abad, Y. Huttel, A. Urbina, A. J. Fernández Romero, Sustainable Energy & Fuels 2020, 4, 4497-4505. https://doi.org/10.1039/D0SE00551G.

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P22- Catalytic activity of MWCNT-based inks synthetized by different methods

S.Lorcaa, F. Santosa, J. Padillaa, A. Urbinab, J.M. González-Domínguezc, E.García-Bordejéc, M.A. Álvarez-Sánchezc, A. Ansón-Casaosc, A. M. Benitoc, W.K.Maserc, A. J. Fernández Romeroa* a Grupo de Materiales Avanzados para la Producción y Almacenamiento de Energía, Universidad Politécnica de Cartagena, Aulario II, Campus de Alfonso XIII, Cartagena. bDepartamento de Electrónica. Universidad Politécnica de Cartagena c Instituto de Carboquimica (ICB-CSIC), Zaragoza (Spain) [email protected]

Research on new catalyst materials for the oxygen reduction reaction (ORR) is the main goal for many research groups around the world, due to its application in fuel cells and metal/air batteries. ORR mainly occurs by two pathways, in alkaline media, the direct four-electron - - transfer pathway from O2 to OH or in a two-steps mechanism, where hydrogen peroxide (HO2 ) is formed in the first reaction. On fuel cells and metal air batteries applications, the catalyst must be optimized to get the oxygen reduced directly to water through the 4 electrons mechanism1. Due to high price of the precious metals, new materials are tested to be used as catalyst in ORR. Among them, researchers have focused their attention mainly on metal oxides, perovskites or carbonaceous materials. 1,5 1,0 0,5 A B 0,0

-1 1,0 -2

) -3 2 -4

N Ewe/V 2 0,5 -5 000 RPM I (mA/cm 100 RPM -6 200 RPM 400 RPM -7 900 RPM 1600RPM -8 2500 RPM 0,0 4000 RPM -9 6400 RPM -10 -1,0 -0,8 -0,6 -0,4 -0,2 0,0 0 20 40 60 80 100 120 140 160 180 20 Ewe (V vs. Hg/HgO) Capacity/mA.h Figure 4: Linear sweep voltammograms curves (Scan rate 50 mV/s in 0,1M KOH) for a MWCNTs based ink (left) and, discharge of a zinc-air battery at -10 mA/cm2 using the same ink as catalyst in the air electrode (right).

In this communication, we have studied four carbonaceous-based inks synthetized by ultrasonic or hydrothermal methods2, using a rotating ring-disk electrode (RRDE) (Figure 1.A). The - - production of HO2 (%HO2 ), transferred electrons and others parameters will be analyzed and the results will be discussed in depth. Finally, the inks were used as catalysts in the cathode of a PVA-KOH-based zinc/air batteries to replace the most widely used catalyst to date, MnO2 (Figure 1.B). Acknowledgements. The authors thank the financial support from Fundación Séneca (Región de Murcia, Spain; Ref: 20985/PI/18 and 19882-GERM-15), Spanish Agencia Estatal de Investigación (PID2019-104272RB- C55/AEI/10.13039/501100011033 and PID2019-104272RB-C51/AEI/10.13039/501100011033), and Gobierno de Aragón (DGA T03_20R). References. (1) Song, C.; Zhang, J. Electrocatalytic Oxygen Reduction Reaction. In PEM Fuel Cell Electrocatalysts and Catalyst Layers: Fundamentals and Applications; 2008; pp 89–134. (2) García-Bordejé, E.; Víctor-Román, S.; Sanahuja-Parejo, O.; Benito, A. M.; Maser, W. K. Control of the Microstructure and Surface Chemistry of Graphene Aerogels via PH and Time Manipulation by a Hydrothermal Method. Nanoscale 2018, 10 (7), 3526–3539.

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P23-Corrosion behavior of 316L stainless steel produced by Direct Metal Laser Sintering

A. Collazo, R. Figueroa, C. Mariño, X.R. Nóvoa, and C. Pérez ENCOMAT Group, University of Vigo, E.E.I. Campus Universitario, 36310 Vigo, Spain [email protected]

The additive manufacturing (AM) is an attractive technique that brings the possibility to create complex free-form objects with a 3D model and an AM printing service. AM was used specifically to create visualization model products, but the developing over time of this technology, by improving the material’s properties, accuracy, and the overall quality, has allowed the output to be suitable for end use 1. AM has a number of advantages such as the possibility of manufacturing complex parts, efficient use of materials without subsequent machining, suitability for low production volumes and manufacturing with a wide variety of metal alloys, as well as the search for new ones. However, the used building parameters produce substantial changes in the microstructure which causes changes in mechanical properties and corrosion behavior. The presence of porosity, residual stress, grain structures, dislocation networks, residual stress, solute segregation, and surface roughness can produce worse properties than traditional manufacturing methods 2. Although, there are already a large number of studies related to the mechanical properties of samples manufactured by AM, there are few studies on corrosion resistance. In recent years, one of the most studied steels is the AISI 316L, although the literature still shows different results with regard to corrosion resistance. The present study aims at evaluating the corrosion behavior of direct metal laser sintered (DMLS) stainless steel AISI 316L. Materials produced by DMLS with different build parameters, input energy density, hatch spacing and traverse speed were compared to wrought 316L. The corrosion properties were investigated using electrochemical corrosion test (cyclic voltammetry (CV) and impedance spectroscopy) in 3.5% NaCl solution. The results show a best performance of DMLS samples for a large number of building parameters. However, the presence of defects for some DMLS samples exhibit high fluctuations as shows figure 1. 10-1 Wrought 316L 10-2 DMLS 316L Defective DMLS 316L

-3

) 10 2

10-4

10-5

10-6

10-7 Current Density (A/cm 10-8

10-9

10-10

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 Potential (V ) SCE Fig. 1. Typical CV for wrought and DMLS 316L after 1 h of immersed in 3.5% NaCl solution

(1) Gibson, I.; Rosen, D.; Stucker, B. Additive Manufacturing Technologies: 3D Printing, Rapid Prototyping; 2015. https://doi.org/10.1007/978-1-4939-2113-3_5. (2) Sander, G.; Tan, J.; Balan, P.; Gharbi, O.; Feenstra, D. R.; Singer, L.; Thomas, S.; Kelly, R. G.; Scully, J. R.; Birbilis, N. Corrosion of Additively Manufactured Alloys: A Review. Corrosion 2018, 74 (12), 1318–1350. https://doi.org/10.5006/2926.

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P24-Synthesis of WO3 nanostructures for photoelectrocatalysis degradation of endocrine disruptors.

M. Cifre-Herrando,a R. M. Fernández-Domene,a,b G-Roselló-Marquez,a D. M. García- Garcíaa, J. García-Antóna

An increase in the presence of new organic compounds, called “emerging pollutants”, has been reported in wastewater and aquatic environments in the last years. Emerging pollutants are new products or chemicals without regulatory status that can be dangerous to human health and the environment due to their toxicity and persistence. Among these emerging pollutants, endocrine disruptors are a family of chemicals that interfere with normal hormonal processes, such as metabolic disorder or breast cancer.

Photoelectrocatalysis (PEC) has emerged as one of the advanced oxidation processes with a great potential for environmental applications, such as removing emerging contaminants from wastewater. WO3 nanostructures are raising increasing attention as an electrode in PEC due to its favorable properties: good conductivity and charge-transfer properties, high stability in acidic solutions, resistance to photocorrosion and ability to absorb visible light.

In the present study, WO3 nanostructures have been synthesized by anodization method in acidic electrolyte. In order to study the formation of the nanostructures and improve their properties, chemicals with different conductivity have been added to the electrolyte: isopropanol and formamide (εisop= 18, εform= 111). The current density registered during the anodization and water splitting tests show that nanostructures synthesized with isopropanol have superior phoelectrochemical properties than those with formamide.

Lastly, the synthesized nanostructures have been used as an electrode in PEC for the degradation of Bisphenol A, an endocrine disruptor detected in wastewaters. The course of the degradation process was controlled by UV-Visible and Ultra High-Performance Liquid Chromatography and Mass Spectrometry (UHPLC-MS-Q-TOF).

Acknowledgments Authors would like to express their gratitude to AEI (PID2019-105844RB-I00/ AEI/10.13039/501100011033) for the financial support and, as well, to E3TECH under project CTQ2017-90659-REDT (MINECO, Spain). M. Cifre-Herrando and G. Roselló-Marquez thank the Generalitat Valenciana for the concession of pre-doctoral grants (ACIF/2020/229 and ACID/2018/159). Finally, project co-funded by FEDER operational programme 2014-2020 of Comunitat Valenciana (IDIFEDER/18/044) is acknowledged.

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P25-Development of conjugated microporous polymer anodes for advanced alkaline rechargeable batteries

Rebecca Griecoa, Nagaraj Patila, Antonio Molinaa, Jesús Palmaa, Marta Lirasb, Jaime S. Sanchezc and Rebeca Marcillaa

aElectrochemical Processes Unit, IMDEA Energy, Avda. Ramón de la Sagra 3, 28935 Móstoles, Spain b Photoactivated Processes Unit, IMDEA Energy, Avda. Ramón de la Sagra 3, 28935 Móstoles, Spain cChalmers University of Technology, Chalmersplatsen 4, 412 96 Göteborg, Sweden [email protected]

The growing demand for large-scale electrochemical energy storage systems necessitates the replacement of the conventional electrodes, that employ transition metal oxides, with more safe, sustainable and low toxicity materials. Among them, redox-active conjugated porous polymers (CPPs) represents an interesting class of low cost and eco-friendly organic electrode materials for energy storage applications (1). Recently, our group highlighted the importance of using CPPs over linear polymers in the battery field, reporting the efficient synthesis of an anthraquinone-based conjugated microporous porous polymer (named IEP-11) via miniemulsion technique and extending this synthetic route to the synthesis of hybrids contianing nanocarbons (2,3). This hybrid CPP showed outstanding electrochemical performance when applied as cathode in Li-ion cell, as high gravimetric (147 mAh g‒1) and areal capacity (6.3 mAh cm‒2), good rate capability, unprecedented long-term cyclability. Here, we take advantage of the versatility of anthraquinone-based materials and report on the benefits of applying IEP-11 microporous polymer also in alkaline aqueous batteries. In particular, we investigated rechargeable dual-ion battery based on commercial Ni(OH)2 cathode and IEP-11 anode using an alkaline electrolyte and then we applied that anode in combination with an improved cathode based on NiCoMnSx structure (4). Our anthraquinone porous polymer appears as good candidate thanks to its robust 3D porous structure that avoids dissolution problems faced by most previous examples in literature. First, we validated this hypothesis by comparing electrochemical performance of IEP-11 || Ni(OH)2 versus linear polymer || Ni(OH)2 full cells in 1 and 10 M KOH. Since cyclability of Ni(OH)2 is also strongly affected by high concentrated electrolyte, we decided to go for an alternative cathode combining our improved IEP-11 anode with novel NiCoMnSx cathode and creating an innovative full-cell that outperformed most of the state-of-the-art alkaline batteries in terms of capacity, energy and power density. These works combinedly demonstrate the applicability of our new polymers towards the development of safe and sustainable rechargeable batteries without compromising in their electrochemical performance. References (1) A. I. Cooper, Conjugated Microporous Polymers; Adv. Mater. 2009, 21, 1291 (2) Molina, A., Patil, N., Ventosa, E., Liras, M., Palma, J., Marcilla, R., 2020. Advanced Functional Materials 30, 6, 1908074 (3) Molina, A., Patil, N., Ventosa, E., Liras, M., Palma, J., Marcilla, R., 2020. ACS Energy Letters 5, 2945–2953. (4) Manuscript in preparation.

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P26-Bidimensional spectroelectrochemistry. A new approach to compare the electrochemical behavior of modified electrode surfaces.

Aranzazu Heras, Pablo López, Fabiola Olmo, Jesús Garoz, Alvaro Colina

Universidad de Burgos, Department of Chemistry, Plaza Misael Bañuelos s/n, E-09001, Burgos, Spain [email protected]

Bidimensional spectroelectrochemistry (Bidim-SEC)1,2 is an analytical technique that allows recording in a single experiment information related to the electron transfer process occurring at the working electrode (WE) surface from three very different points of view. The first one comes from the electrochemical signal that includes all the aspects directly related to the oxidation or reduction process provoked by the potential or current applied to the electrochemical system. The other two arise from simultaneously recording the spectral changes taking place during the electron transfer process. Specifically the electromagnetic radiation samples the solution adjacent to the WE in a normal (perpendicular) and parallel direction respect to it, deconvolving the information related to the processes mainly occurring at the WE surface and those taking place exclusively on the diffusion layer.

In this work, a new cell (Fig. 1) is developed that allows two Bidim-SEC experiments to be performed at the same time. In this way, it is possible to compare in the same experiment, for example, the consequences or effects that the modification of the electrode surface has with respect to the process of oxidation or reduction of a certain molecule. The new Bidim-SEC cell is tested modifying partially a HOPG surface with a thin film of SWCNTs and comparing the electrochemical and spectroscopic response of different molecules such as ferrocenomethanol (takes as test molecule), dopamine or 3,4- ethylenedioxythiophene.

ACKNOWLEDGMENTS Authors acknowledge the financial support from Ministerio de Economía y Competitividad (Grants CTQ2017-83935-R-AEI/FEDER, UE), Ministerio de Ciencia, Innovación y Universidades (RED2018-102412-T) and Junta de Castilla y León (Grant BU297P18). F.O. thanks its contract funded by Junta de Castilla y León, the European Social Fund and the Youth Employment Initiative. J.G.R. thanks Ministerio de Economía y Competitividad for his postdoctoral contract (CTQ2017- 83935-R AEI/FEDER, UE).

REFERENCES (1) López-Palacios, J.; Colina, A.; Heras, A.; Ruiz, V.; Fuente, L. Anal. Chem. 2001, 73, 2883. (2) Garoz-Ruiz, J.; Heras, A.; Palmero, S.; Colina, A. Anal. Chem. 2015, 87, 6233.

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P27-An study of the eCoCell gas diffusion layer in a open cathode FCPEM

A.J. Navarro, M.A. Gómez and J.J. López Cascales Universidad Politécnica de Cartagena, Dep. Ing. Química y Ambiental Campus de Alfonso XIII, Aulario C, 30203, Cartagena Murcia, Spain. [email protected]

Fuel cells are electrochemical devices that transforms the hydrogen chemical energy into electrical current [1], based on the hydrogen oxidation and the oxygen reduction. Among other types of fuel cells, an open cathode proton exchange membrane fuel cell (OC-PEMFC) is a type of fuel cell in which oxygen is taken from the environment by air convection using an external fan [2]. A gas diffusion layers (GDL) is an anisotropic system, and its performance in a fuel cell is associated with its porous morphology, electrical conductivity, thermal conductivity and hydrophobicity. In this context, several studies have been carried out to scout the role played by the GDLs on the performance and durability of fuel cells, and how certain GDL characteristics, such as their thickness or pore size distribution, affect to the fuel cell performance [3]. This work is focused on the characterization of a novel gas diffusion layer called eCoCell that has been developed in our laboratory and commercialized by Hydrogreen Energy S.L. (www.hydrogreenergy.com). In this sense, the porous distribution function, gas permeability, electrical conductivity, thermal conductivity and water evaporation rate was investigated as a function of the temperature. The results of the above characterization were compared with the obtained ones from a commercial Sigracet grade.

Bibliography [1]Spiegel, C.S. “Designing and Building Fuel Cells”, The McGraw-Hill, 2007. [2] Z. Huang and A. Su and C. Hsu and Y. Liu , Fuel 122, 76-81, 2014. [3] P.H. Maheshwari and C. Gupta and R.B. Mathur, Fuel Cells 14, 566-753, 2014.

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P28-Guidelines for the Voltammetric Study of Electrode Reactions with Coupled Chemical Kinetics at an Arbitrary Electrode Geometry

Manuela López-Tenés, Eduardo Laborda and Angela Molina

Departamento de Química Física, Facultad de Química, Regional Campus of International Excellence“Campus Mare Nostrum”,Universidad de Murcia, 30100 Murcia, Spain [email protected]

By suitable preliminary analysis of the boundary value problem, a remarkable generalization and simplification of the theoretical treatment of homogeneous chemical reactions affecting the interfacial charge transfer is revealed for any electrode size and shape 1,2. Thus, the multivariable boundary value problem of complex reaction mechanisms 3, at both uniformly accessible (as(hemi)spheres) and non-uniformly accessible (as discs) electrodes, can be reduced to a single variable problem the mathematical form of which is equivalent to that of an irreversible E mechanism. This is obviously very advantageous for the mathematical resolution of the problem either by analytical or numerical methods.

In this communication, the use of the above theoretical approach is illustrated by treating the problem of the SQ mechanism and the simpler derived schemes oSQ, CEC, CE and EC 4,5. The solutions obtained enable the comprehensive study of their voltammetric response as a function of the chemical rate and equilibrium constants and of the electrode size and shape. As a result, clues and experimental protocols for the identification and characterization of the charge transfer mechanism and for the determination of the corresponding kinetic and thermodynamic parameters are established. Also, the equivalence relationship between electrodes of different shape is critically examined within this context, finding that the constant relationship between the steady state current−potential response at microdiscs and micro(hemi)spheres (ratio between the current densities at electrodes of the same radius = 4/π) does not hold in the presence of chemical kinetic effects, even though the electron transfer is Nernstian.

Acknowledgements Fundación Séneca - Agencia de Ciencia y Tecnología de la Región de Murcia (19887/GERM/15).

References (1) López-Tenés, M.; Laborda, E.; Molina, A.; Compton, R.G. Anal. Chem. 2019, 91, 6072-6079. (2) Molina, A.; López-Tenés, M.; Laborda, E. Electrochem.Commun. 2018, 92, 48−55. (3) Molina, A.; Laborda, E. Electrochimica Acta 2018, 286, 374-396. (4) Morales, I.; Molina, A. Electrochem. Commun. 2006, 8, 1453-1460. (5) Molina, A.; Morales, I.; López-Tenés, M. Electrochem. Commun. 2006, 8, 1062-1070.

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P29-Carbon electrodes modified with clusters of copper nanoparticles. Use as sensors for the determination of antioxidant capacity.

María Teresa Moreno and José Miguel Rodríguez Mellado Departamento de Química Física, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, Spain. [email protected]

The assessment of antioxidant activity is a goal for the food industry from many years. The quantification of such activity has derived in the development of new methods, to overcome the limitations of the classical spectrophotometric methods as CUPRAC, which is based in the reduction of Cu2+ ions, and is limited by the working pH and the color and turbidity of the sample. Electrochemical methods have been recently reported [1], but they present limitations dealing with the stability in non-aqueous media and the complexity of their preparations. The aim of this work was to develop and characterize electrodes able to assess the antioxidant activity for a wide range of samples. These sensors of antioxidant capacity are based on the electrodeposition of copper on glassy carbon electrodes (GCE).

The voltammetric reduction signal of Cu2+ ions has been studied to establish the potentials where the growth rate is controlled by the mass transfer. In these conditions the charge-transfer is fast, and nucleation occurs. The different deposition parameters as potential and time of copper electrodeposition were optimized. The optimized deposition medium was 0.5 M CuNO3 solutions, in nitric acid. The resulting modified electrodes were characterized by SEM.

The sensors were used in phosphate buffer solution at pH 7 (near to physiological conditions). From the monitoring of the anodic and cathodic peaks in cyclic voltammetry, the stability and reproducibility of the electrodes were established. The electrochemical responses were related to the structure of the surfaces observed by SEM. As can be seen in figure 1, the morphology of the clusters of nanoparticles is modified along the experiments. Antioxidants as Ascorbic and Gallic acids added to the medium originate a decrease of the reduction peak, which is lower as the antioxidant concentration increases. So, the copper-modified electrode serves as sensor for the antioxidant capacity.

Figure 1. SEM images of the ECV after 60 seconds of deposition in 0.5 M HNO3 at –0.3 V, followed by a single scan in cyclic voltammetry. Acceleration voltage 5.0 kV. Working distance 18 mm.

(1) M.P. Rivas Romero, M.P.; Estévez Brito, R.; Palma, A; Ruiz Montoya, M. Rodríguez Mellado, J.M.; Rodríguez-Amaro, R. J. Electrochem. Soc. 2017, 164, B97 (and references cited).

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P30-Electrochemical detection of pungency of Capsicum annuum cubana red extracts

María Teresa Moreno, Rafael Estévez Brito, Marina Córdoba and José Miguel Rodríguez Mellado Departamento de Química Física, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, Spain. [email protected]

Capsaicin (8-methyl-N-vanillyl-6-nonenamide), is a phenolic compound responsible for the characteristic taste and pungency of chili peppers, representing up to 1% of their weight, being the most consumed condiment by humans, together with salt. The pungency level of spices was first evaluated with the Scoville Organoleptic Test, which express the pungency level in a scale called the Scoville Heat Unit (SHU). This is subject to a great error (c.a. 50% for the same extract) because the different perception of the operators. Today pungency is determined by multiplying the capsaicin plus dihydrocapsaicin content in grams in one gram of food by 1.6ꞏ106 SHU. Peppers, in general, and chili peppers, in particular, are rich in ascorbic acid. The objective of this communication is to propose an easy, fast, sensitive and inexpensive method for determining the pungency and ascorbic acid content in chili pepper extracts.

The voltammetric (cyclic and differential pulse) behavior of capsaicin on a glassy carbon electrode has been evaluated at different pH values. A calibration curve for capsaicin is obtained in differential pulse voltammetry in PBS solution at pH 7.0. The voltammograms of the extracts showed a peak corresponding to ascorbic acid at potentials near to 0.1 V and (in the case of the ethanolic extract of cubana red) the peak corresponding to capsaicin, at potentials near to 0.3 V. Thus, to obtain the pungency it is necessary to separate the two contributions. A variant of the standard addition method is used for simultaneous determination of the pungency and ascorbic acid content of extracts of Capsicum annuum cubana red. Different volumes of a solution of 0.01 M ascorbic acid were successively added to the extract and the corresponding differential pulse voltammograms were recorded. The ascorbic acid content is compared to that of a sweet pepper. The method is cheap, simple and rapid, its sensitivity being comparable to other more expensive and/or more laborious methods.

Figure 1. Differential pulse voltammograms of 2mL cubana red ethanolic extract in 48 mL of PBS at pH=7.0 and variable volumes of 0.01 M ascorbic acid. Plot of the net currents at the potentials given in the graph vs. ascorbic acid volume added.

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P31-Superior carbon-based electrocatalysts decorated with iron complexes towards the oxygen reduction reaction

Beatriz Martínez-Sáncheza, Diego Cazorla-Amorósb and Emilia Morallóna

a Departamento de Química Física and Instituto Universitario de Materiales de Alicante (IUMA), University of Alicante, Ap. 99, 03080, Alicante, Spain b Departamento de Química Inorgánica and Instituto Universitario de Materiales de Alicante (IUMA), University of Alicante, Ap. 99, 03080, Alicante, Spain [email protected]

The current growth in global energy demand, the overexploitation of natural resources, the waste management problems and the increasing emissions of greenhouse gases to the environment, have led to intensive research into efficient, clean and sustainable energy alternatives. The oxygen reduction reaction (ORR) is of great relevance in many renewable and energy-saving technologies, such as fuel cells, metal-air batteries or solar cells. To solve the sluggish nature of the ORR kinetics and to permit a massive deployment in all energy industries, it is necessary to design more efficient, durable and cheaper alternatives to the state-of-the-art electrocatalysts based on precious metals. On this search, iron (II) phthalocyanines (FePc) supported on nanostructured carbon materials have highlighted as extraordinary electrocatalysts in alkaline medium1,2. In this study, hybrid materials based on FePc and Carbon Nanotubes (CNTs) were prepared by the incipient wetness impregnation method. A theoretical amount of 1 % wt. Fe is supported onto the CNTs, which has been confirmed by XPS. Two different structures of CNTs were studied as support, both the Single-Walled and Herringbone Carbon Nanotubes (SWCNTs and hCNTs, respectively). Moreover, the effect of the electrochemical functionalization of CNTs with N and P-containing species was analyzed. It was found that these heteroatoms can act not only as ligands of the FePc, but also regulate the reactivity of the metal center, thus improving the stability and selectivity of the final materials. Nevertheless, the presence of heterogeneous oligomeric chains can make difficult the correct distribution of FePc over the surface of CNTs, which affects the high intrinsic catalytic activity. Interestingly, the FePc-hCNTs catalysts overcome the electrocatalytic performance of commercial Pt/C catalyst towards the ORR in alkaline medium, with comparable onset potential, electron transfer rate and significatively higher limiting current. These results reveal a possible scalable alternative for the synthesis of high catalytic activity materials towards the ORR.

(1) Yang, J.; Tao, J.; Isomura, T.; Yanagi, H.; Moriguchi, I.; Nakashima, N. A Comparative Study of Iron Phthalocyanine Electrocatalysts Supported on Different Nanocarbons for Oxygen Reduction Reaction. Carbon. 2019, 145, 565–571. https://doi.org/10.1016/j.carbon.2019.01.022. (2) Zagal, J. H.; Griveau, S.; Ozoemena, K. I.; Nyokong, T.; Bedioui, F. Carbon Nanotubes, Phthalocyanines and Porphyrins: Attractive Hybrid Materials for Electrocatalysis and Electroanalysis. J. Nanosci. Nanotechnol. 2009, 9 (4), 2201–2214. https://doi.org/10.1166/jnn.2009.SE15.

Acknowledgements: B.M.-S. thanks the Ministry of Science, Innovation and Universities of Spain for the FPU grant (FPU18/05127). The authors would like to thank MINECO and FEDER (PID2019-105923RB-100 and RTI2018-095291-B-I00) for the financial support.

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P32-Ni nanoparticles supported on graphene-based materials for the oxygen reduction reaction in alkaline medium

a a a b Sthephanie J. Martínez , José L. Rodríguez , Elena Pastor and Germán Noriega a Instituto de Materiales y Nanotecnología, Departamento de Química, Universidad de La Laguna, PO Box 456, 38200, La Laguna, Santa Cruz de Tenerife, Spain b CIDETE INGENIEROS SL, Av. Marítima 68, Candelaria, Santa Cruz de Tenerife, Spain [email protected]

The development of new energy systems that are renewable and environmentally friendly is crucial to fulfil the growing energy demand. In this context, graphene-based materials (GMs) have emerged as an outstanding support for fuel cells catalysts (1,2). Furthermore, GMs also improve the dispersion and distribution of metallic nanoparticles, and therefore, an intensification of the catalytic activity toward several reactions was usually observed (2). The development of catalysts for the oxygen reduction reaction (ORR) at the cathode of polymer electrolyte fuel cells (PEMFCs) is one of the keys for the improvement of the overall performance of these devices. Accordingly, in this work, graphene-based materials doped with nitrogen and sulphur were synthesized employing caffeine and ammonium thiocyanate, both as doping and reducing agent, to study their electrocatalytic activity towards the ORR. Ni nanoparticles were supported on these materials with a nominal metallic loading of 20 wt. % by the sodium borohydride reduction method. X-ray diffraction, scanning electron microscopy coupled with energy dispersive X- ray, elemental analysis and infrared spectroscopy techniques were used to characterize the materials. Additionally, the electrocatalytic activity was evaluated towards the ORR by means of cyclic voltammetry, linear sweep voltammetry and rotating ring- disk electrode.

References (1) Rivera, L.M; García, G., & Pastor, E. Novel Graphene materials for the oxygen reduction reaction. 2018, 9, 223-239. (2) Liu J et al. Pt0.61Ni/C for High-Efficiency Cathode of Fuel Cells with Superhigh Platinum Utilization. 2018, 122 (26), 14691-14697.

Acknowledgements The Spanish Ministry of Science and Innovation (MICIIN) has supported this work under project ENE2017-83976 -C2-2-R (co-funded by FEDER). S.J.M acknowledges the ACIISI for the predoctoral grant (TESIS2019010150).

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P33-Organic-Inorganic Sol-Gel s(SEBS/GPTMS-MPTMS) Membranes for PEMFCs

J. Mosa,a M. Aparicioa, F.O. Díaza,b, E. Moralesb and C. del Río,b

aInstituto de Cerámica y Vidrio (CSIC), Kelsen 5, 28049 Madrid, Spain. bInstituto Ciencia y Tecnología Polímeros (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain [email protected]

Many studies have been devoted to the development of new proton exchange membranes for low temperature fuel cells (PEMFCs) presenting a suitable dimensional stability, high ionic conductivity and low cost for a significant volume production, among them, block copolymer ionomers based on styrenic thermoplastic elastomers bearing sulfonic acid groups. The introduction of ionic groups into the polystyrene blocks causes significant changes in many physical properties, not only the emergence of ionic conductivity but also changes in hydrophilicity and mechanical strength, not detected in their non-ionic counterparts. SEBS (styrene-ethylene-butylene-styrene) triblock copolymer is a commercial and economical material which is obtained by hydrogenation of the thermoplastic elastomer of styrene and butadiene, eliminating the unsaturation of the butylene chain. After sulfonation, via electrophilic substitution, nanometer scale phase separated morphology of hydrophilic and hydrophobic domains is generated providing proton mobility paths in wet state which makes sulfonated SEBS (sSEBS) very attractive for its use in fuel cells. Unfortunately, a high degree of sulfonation is often required to achieve suitable proton conductivity which causes excessive swelling in water and loss of dimensional stability with moderate cell performance and durability. An interesting strategy to reduce water uptake and improve mechanical properties is the development of hybrid organic-inorganic membrane materials with covalent bonds between components, using the sol-gel method (1,2).

The inorganic component chosen in this work is itself a hybrid (organic-inorganic) consisting of (3-glycidoxypropyl) trimethoxysilane (GPTMS) and 3-mercaptopropyl trimethoxysilane (MPTMS) in a molar ratio of 30/70. The hybrid membranes were prepared from chloroform solutions of SEBS/(GPTMS-MPTMS) mixtures with different compositions. Before performing the sulfonation reaction of SEBS aromatic rings the thiol groups of MPTMS were oxidized to sulfonic acids to ensure higher proton mobility.

The effect of (GMTMS-MPTMS) proportion in the resulting hybrid membranes is studied in order to their future application as electrolytes in PEMFC. Thus, the s(SEBS-GPTMS-MPTMS) hybrid sol-gel membranes are compared with neat sSEBS and characterized in terms of swelling ratio and area increase in water, IEC, thermal stability, morphology, proton conductivity and performance in single H2/O2 fuel cells.

(1) Escribano, P.G.; del Río, C.; Morales, E., Aparicio, M.; Mosa, J. J. Membr. Sci. Infiltration of 40SiO2−40P2O5−20ZrO2 sol-gel in sSEBS membranes for PEMFCs application 2018, 551C, 136. (2) Santiago, Ó.; Mosa, J.; Escribano, P.G.; Navarro, E.; Chinarro, E.; Aparicio, M.; Leo, T.J.; del Río, C. Int. J. Hydrogen Energ Sol-gel infiltrated sSEBS membranes with improved methanol crossover and cell performance for direct methanol fuel cell applications 2020 https://doi.org/10.1016/j.ijhydene.2020.01.252.

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P34-40SiO2- 40P2O5- 20ZrO2 sol-gel infiltration in sSEBS membranes: performance analysis of DMFC and PEMFC fuel cell applications

J. Mosaa*, Ó. Santiagob,c, P.G. Escribanod, E. Navarroc, E. Chinarroa, T.J. Leob, M. Aparicioa, C. del Ríod

a Instituto de Cerámica y Vidrio (ICV-CSIC), Kelsen 5, 28049 Madrid, Spain. b Dept. Arquitectura, Construcción y Sistemas Oceánicos y Navales, ETSI Navales, Universidad Politécnica de Madrid, Avda. de la Memoria 4, Madrid 28040, Spain. c Dept. Mecánica de Fluidos y Propulsión Aeroespacial, ETS Ingeniería Aeronáutica y del Espacio, Universidad Politécnica de Madrid, Plz. Cardenal Cisneros 3, Madrid 28040, Spain. d Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain. [email protected]

Clean and effective energy conversion technologies, such as proton exchange membrane fuel cells (PEMFCs) including direct methanol fuel cells (DMFCs), have remodeled the future of power supply systems for electric vehicles, portable electronics and backup power sources. A key factor in the commercialization of PEMFCs and DMFCs is the development of membrane electrode assemblies (MEAs) featuring high performance, low cost and acceptable lifetime. As a core component of PEMFCs, the polymer electrolyte is a vital factor that determines the performance and influences the cost of fuel cells. Most present day DMFC designs are based on polymer membrane fuel cell technology using acid electrolyte membranes being the most common electrolytes. Methanol and water transport is one of the key challenges to solve in DMFC system comparing to PEMFC. The main purpose is to provide enhanced conductivity at a reduced methanol crossover. State-of-the-art Nafion® membrane presents adequate conductivity for DMFC devices but the methanol permeability for this polymer electrolyte is unfortunately also significant. SEBS, styrene-ethylene-butylene-styrene triblock copolymer (SEBS) is an interesting and low cost raw material for fuel cell applications as it becomes a proton conducting ionomer by direct sulfonation reaction of styrenic units. Nevertheless, although low cost electrolyte sSEBS membranes with high proton conductivity can be easily synthetized they experience an unacceptable loss of dimensional stability and mechanical weakness in wet state that seriously compromises their lifetime and durability. An interesting attempt to prevent these mechanical limitations as well as controlling methanol crossover in DMFC is the preparation of hybrid organic-inorganic membranes by combining sSEBS with nano-scale inorganic sol-gel infiltration (1,2). The sol-gel infiltration method accommodates onto existing sSEBS hydrophilic regions, so the resultant interpenetrating proton-conducting membranes often lead to an improvement in mechanical strength and methanol barrier properties. The present work was addressed to study the effect of infiltration time on properties such as methanol permeability and proton conduction with the aim to investigate their influence on the PEMFC and DMFC performance. (1) Escribano, P.G.; del Río, C.; Morales, E., Aparicio, M.; Mosa, J. J. Membr. Sci. Infiltration of 40SiO2−40P2O5−20ZrO2 sol-gel in sSEBS membranes for PEMFCs application 2018, 551C, 136. (2) Santiago, Ó.; Mosa, J.; Escribano, P.G.; Navarro, E.; Chinarro, E.; Aparicio, M.; Leo, T.J.; del Río, C. Int. J. Hydrogen Energ Sol-gel infiltrated sSEBS membranes with improved methanol crossover and cell performance for direct methanol fuel cell applications 2020 https://doi.org/10.1016/j.ijhydene.2020.01.252

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P35-Increasing the selectivity towards nitrates of recycled anion exchange membranes for electro-separation processes

Amaia Lejarazu-Larrañaga1,2, Serena Molina1, Juan Manuel Ortiz1, Eloy García-Calvo1,2 1IMDEA Water Institute, Avenida Punto Com, 2, Parque Científico Tecnológico de la Universidad de Alcalá, 28805, Alcalá de Henares, Madrid, Spain. 2Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering Department, Universidad de Alcalá, Alcalá de Henares, Spain. [email protected]

Membrane separation using ion exchange membranes (IEMs) is an economical and environmentally friendly separation method for aqueous solutions. In this sense, it represents an alternative to recover and reuse nitrogen from wastewater in a sustainable way, being a promising solution to shift wastewater treatment from standard treatment to current emphasis on sustainability. This work shows a simple, low cost and scalable method for the preparation of nitrate-selective AEMs. The selectivity of the membranes for target could be easily tuned up by selecting the appropriate ion exchange resin, in this way a large variety of selective membranes could be conveniently prepared.

a) 50 b) 50

t 2‐= 0.19 t 2‐= 0.18 SO SO 45 4 45 4

40 40 t ‐= 0.29 Cl (mM) ‐ (mM )

t = 0.29 35 Cl 35

30 30 t ‐ = 0.53 NO 3

25 t ‐ = 0.53 NO 25 Chloride 3

Concentration Chloride 20 Concentration 20 Nitrate Nitrate 15 Sulphate 15 Sulphate 0 30 60 90 120 150 0 30 60 90 120 150 Time (min) Time (min)

-2 Figure 1. Selective separation at 5 mA·cm ; a) AEM prepared without using mechanical support, b) AEM prepared using a recycled pressure filtration membrane as mechanical support “t” is the

The results revealed that the prepared membranes can effectively facilitate the transport of nitrates over other monovalent and multivalent anions. The use of low current density significantly improves the separation efficiency and facilitates the transport of nitrates through the membrane.

ANKNOWLEDGEMENTS This research is part of contract for training doctors (FPI, BES-2016-076244) and the program CTM2015-74695-JIN (AEI/FEDER, UE). Support from the E3TECH Excellence Network under project CTQ2017-90659-REDT (MCIUN, Spain) is also acknowledged.

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P36-Electrochemical, Attenuated Total Reflection-Surface Enhancement Infrared Absorption Spectroscopy (ATR-SEIRAS) and DFT study of the adsorption of 5-methylcystosine on gold electrodes.

Francisco Prieto Dapena, Manuela Rueda, Virginia García

aUniversity of Seville, Department of Physical Chemistry. c/ Profesor García González 1. 41012. Seville. SPAIN [email protected]

Watson-Crick interactions between complementary bases of DNA are responsible for the correct replication of genetic material.1 These specific interactions are more likely to happen when the bases are in their canonical form, while the presence of "unstable" tautomeric forms can produce non-complementary base interactions,2,3 introducing errors in the base sequence of the DNA chain. Among the different factors that can affect the different tautomers of the DNA bases are the pH and the presence of substituents. One of the most relevant marks from the epigenetic point of view is the methylation of bases. For instance, the introduction of a methyl group at position 5 of the cytosine4 is related to neuronal development that can lead to Alzheimer's diseases, and with the inactivation of transcription of tumor suppressor genes. In a previous work, the tautomeric behavior of cytosine adsorbed on gold electrodes was investigated.5 The results showed the preponderance of the canonical oxo-amine tautomeric form of cytosine in solution. However, in adsorbed state the oxo-imine tautomer is the preponderant one, although the presence of the oxo-amine could be inferred for the ATR- SEIRA spectra at low potentials. This communication contains the study, by means of electrochemical and ATR-SEIRAS measurements and DFT calculations, of the adsorption of 5-methylcytosine on gold electrodes, the tautomeric forms presents in solution and in adsorbed state and the influence of the electrode potential in the tautomeric stability.

(1) Watson, J. D.; Crick, F. H. C. Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid. Nature 1953, 171 (4356), 737–738. https://doi.org/10.1038/171737a0. (2) Wang, W.; Hellinga, H. W.; Beese, L. S. Structural Evidence for the Rare Tautomer Hypothesis of Spontaneous Mutagenesis. Proc. Natl. Acad. Sci. 2011, 108 (43), 17644– 17648. https://doi.org/10.1073/pnas.1114496108. (3) Ceron-Carrasco, J. P.; Jacquemin, D.; Cauet, E.; Cerón-Carrasco, J. P.; Jacquemin, D.; Cauët, E. Cisplatin Cytotoxicity: A Theoretical Study of Induced Mutations. Phys. Chem. Chem. Phys. 2012, 14 (36), 12457–12464. https://doi.org/10.1039/c2cp40515f. (4) Bird, A. DNA Methylation Patterns and Epigenetic Memory. Genes Dev. 2002, 16, 6– 21. https://doi.org/10.1101/gad.947102. (5) Alvarez-Malmagro, J.; Prieto, F.; Rueda, M. In Situ Surface Enhanced Infrared Absorption Spectroscopy Study of the Adsorption of Cytosine on Gold Electrodes. J. Electroanal. Chem. 2019, 849, 113362. https://doi.org/10.1016/J.JELECHEM.2019.113362.

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P37-Direct determination of monosaccharides in honey by coupling a sensitive new schiff base Ni complex electrochemical sensor and chemometric tools

M. Revenga-Parraa,b,c, S. N. Robledod, E. Martínez-Periñána, M. M. González-Quirósa, A. Colinae, A. Herase, F. Parientea,b,c and E. Lorenzoa,b,c

1 Departamento de Química Analítica y Análisis Instrumental and 2Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain. 3 IMDEA-Nanoscience. Faraday 9, Campus Cantoblanco-UAM, 28049 Madrid, Spain. 4 Departamento de Tecnología Química, Facultad de Ingeniería, Universidad Nacional de Río Cuarto, 5800 Río Cuarto, Argentina. 5Departamento de Química, Universidad de Burgos, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain. [email protected]

The determination and quantification of saccharides is of considerable importance in the food industry among other fields. In this work, we describe for the first time the preparation of a new Schiff base Ni complex, NiII-(N,N’-bis(2,3-dihydroxybenzylidene)-1,2-diaminobenzene) obtained by reaction of the tetradentate Schiff base ligand containing ortho quinone functional groups (N,N’-bis(2,3-dihydroxybenzylidene)-1,2-diaminobenzene) and Ni2+, as well as its application in the development of an electrochemical sensor. Coupled to chemometric tools, the sensor allowed the direct determination of glucose and fructose in honey, without the need of previous separation steps or chromatographic techniques. For this purpose, the new Schiff base Ni complex has been electropolymerized onto screen-printed electrodes modified with carbon nanotubes. The electropolymerization process has been exhaustively characterized by operando spectroelectrochemical techniques to confirm the presence of conductive polymeric film that presents a high adherence to the electrode surface. The resulting modified electrodes show a stable cyclic voltammetric response and present a potent and persistent electrocatalytic activity towards the oxidation of glucose and fructose in alkaline solution and have been employed in combination with partial least squares regression (PLSR) to resolve mixtures of glucose and fructose in a complex matrix, as honey. The multivariate model was based on PLSR analysis and showed good predictive capability for the two analytes in sample standard honey with an average error of 8% and relative standard deviations below 9%.

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P38-Metal Nanoparticle/Electrolyte Interface on the Electrocatalytic Performance of Gold and Silver Nanoparticles for Oxygen Reduction Reaction

José Á. Salatti-Dorado,a Valentín García-Caballero,a Manuel Cano,a and Juan J. Giner- Casaresa

a Departamento de Química Física y Termodinámica Aplicada, Instituto Universitario de Nanoquímica (IUNAN), Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Ed. Marie Curie, E-14071 Córdoba, Spain. [email protected]

Oxygen reduction reaction (ORR) is a cathodic process involved in fuel cells and metal-air batteries, requiring the presence of electrocatalyst materials to lower their overpotentials and promote practical applications of related energy devices.1 Although ORR can be performed in acidic and basic media, alkaline electrolytes considerably improve the ORR activity and selectivity toward the four-electron pathway, which is highly desirable for fuel cell application.2 Plasmonic nanoparticles (NPs) are considered excellent ORR electrocatalysts under alkaline conditions.3,4 Herein, citrate-stabilized silver NPs and gold NPs with similar particle size (ca. 15 nm) were synthesized. After exhaustive characterization using UV-visible absorption spectroscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, the electrocatalytic performance of both plasmonic NPs for ORR was compared in different alkaline electrolytes (LiOH, NaOH and KOH), both under static and dynamic conditions. Overall, AuNPs@Citrate provides better electrocatalytic features than AgNPs@Citrate for ORR, both in terms of onset potential and maximum current density values. NaOH appears as the most appropriate electrolyte for ORR with AgNPs@Citrate, whilst KOH is the more appropriate for ORR with AuNPs@Citrate. Our finding demonstrate that the cation specie contained in the electrolyte infers on the electrochemical behaviour of both plasmonic NPs through the metal-liquid interface, which in turns is involved into a number of processes, such as desorption of adsorbed water, modification of the local ionic environment and the electrical double layer.

Acknowledgements: MANA project CTQ2017-83961-R, JEANS project CTQ2017-92264- EXP and RyC-2014-14956 from Ministry of Science and Innovation of Spain. UCO-1263193 project from the Andalusian Government of Spain.

References: (1) Moureaux, F.; Stevens, P.; Chatenet, M. Electrocatalysis 2013, 4, 123–133. (2) Ignaczak, A.; Nazmutdinov, R.; Goduljan, A.; Moreira de Campos Pinto, L.; Juarez, F.; Quaino, P.; Santos, E.; Schmickler, W. Nano Energy 2016, 26, 558–564. (3) Shi, F.; He, J.; Zhang, B.; Peng, J.; Ma, Y.; Chen, W.; Li, F.; Qin, Y.; Liu, Y.; Shang, W.; Tao, P.; Song, C.; Deng, T.; Qian, X.; Ye, J.; Wu, J. P. Nano Lett. 2019, 19, 1371–1378. (4) Alba-Molina, D.; Santiago, A. R. P.; Giner-Casares, J. J.; Rodríguez-Castellón, E.; Martín-Romero, M. T.; Camacho, L.; Luque, R.; Cano, M. J. Mater. Chem. A 2019, 7, 20425– 20434.

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P39-Surface characterization of Cu catalysts by lead underpotential deposition

Paula Sebastián Pascual,a María Escudero-Escribanoa

a Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark

[email protected]

Cu electrodes are model catalysts for a wide variety of interesting reactions such as CO2 and CO conversion into fuels.1 Structure sensitivity plays a key role in the mechanism of different electrocatalytic reactions. However, quantifying the presence of different domains on Cu electrocatalysts is a challenge. This is mainly due to their blank cyclic voltammograms offer little information about the facet distribution of non-well defined surfaces.2,3 Herein, we investigate the lead underpotential deposition (UPD) on roughened and well-defined Cu electrode in presence of chloride, as a tool to assess the state of the surface and determine the presence and distribution of domains on Cu catalysts. The voltammetric profile of lead UPD is strongly sensitive to the changes in the structure of the Cu electrode, allowing to monitor the appearance of new defects and domains. We highlight that lead UPD could be used to provide the electrochemical fingerprint of a large variety of Cu catalysts, including nanostructured surfaces.4

150 Cu (111) A Cu(poly) B Cu(100) 100 roughened Cu(poly) 100 Cu(poly)

50 50 -2

0 A cm 0 

j / -50 -50 -100 <111> -150 <100> and -100 defect sites

-0.4 -0.3 -0.2 -0.4 -0.3 -0.2 E / V vs SCE E / V vs SCE

Figure 1: Lead UPD from a 2 mM PbClO4 + 0.1 M KClO4 + 1mM NaCl solution in A) Cu(poly) and Cu(hkl), B) Electrochemically roughed Cu(poly) and flat Cu(poly). 50 mV/s.

(1) Sebastián-Pascual, P.; Mezzavilla, S.; Stephens, I. E. L.; Escudero-Escribano, M. ChemCatChem 2019, 21 (0), 3626–3645. (2) Sebastián-Pascual, P.; Escudero-Escribano, M.. ACS Energy Lett. 2020, 5 (1), 130– 135. (3) Sebastian-Pascual, P.; Sarabia, F. J.; Climent, V.; Feliu, J. M.; Escudero-Escribano, M. . J. Phys. Chem. C 2020, 124 (42), 23253–23259. (4) Sebastian-Pascual, P.; Escudero-Escribano, M. Submitted 2021.

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P40-Green electrosynthesis of 4-aminophenol by using electrodeposited porous Au micropillars

Albert Serrà,a Maxime Tranchant,a Christopher Gunderson,a Jaume García‐Amorós,b,c Elvira Gómez,c,d and Laetitia Philippea

a Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, CH-3602 Thun, Switzerland. b Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franquès, 1, E-08028 Barcelona, Catalonia, Spain. c Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Martí i Franquès, 1, E-08028, Barcelona, Catalonia, Spain. d Departament de Ciència de Materials i Química Física, Universitat de Barcelona, Martí i Franquès, 1, E-08028, Barcelona, Catalonia, Spain. [email protected]

Using 4-aminophenol as an intermediate in manufacturing analgesic and antipyretic drugs has given the product important commercial value. Currently, several methods are available for synthesizing 4-aminophenol, the most relevant being the multistep iron-acid reduction of 4- nitrochlorobenzene or 4-nitrophenol, the catalytic hydrogenation of nitrobenzene, and the electrochemical reduction of 4-nitrophenol. However, the necessary use of highly corrosive mineral acids and dangerous toxic reducing agents, poor chemoselectivity and yields, and the growing demand for 4-aminophenol demonstrate the need for developing or optimizing green, efficient routes for preparing 4-aminophenol. Among possible options, organic electrosynthesis can realize an environmentally friendly, chemoselective redox transformation under conditions free of exogenous reductants due to the use of electric current. However, the optimization of efficient electrocatalysers and electrochemical media conditions needs to be further studied to propose such a route for synthesizing 4-aminophenol. In the study reported here, the electrosynthesis of highly accessible, well-defined porous Au micropillars for use as electrocatalyzers in the chemoselective electroreduction of 4-nitrophenol was optimized. Using the double shape-controlled electrodeposition of Au based on the combination of 3D laser lithography and colloidal lithography allowed the reproducible synthesis of porous Au micropillars with highly accessible surface areas. Figure 1: (a) FE-SEM micrographs. Additionally, using the porous Au micropillars in Scale bar: 2 µm. (b) Time-dependent UV- moderately acidic conditions realized the vis spectra at 20 °C. electrosynthesis of 4-aminophenol, both in high yields and with high chemoselectivity. Porous Au micropillars can thus also contribute to an efficient, environmentally friendly method of removing 4-nitrophenol from wastewater. The electrosynthesis of porous Au micropillars as electrocatalyzers for 4-nitrophenol reduction can offer a competitive, ecofriendly strategy for electrosynthesizing 4-aminophenol or decontaminating wastewater. Acknowledgment. Albert Serrà would like to acknowledge funding from the EMPAPOSTDOCS-II program (Marie Sk1odowska-Curie grant agreement number 754364).

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P41-Testing new MMO/ZnO electrodes in the photoelectrocatalysis of Levofloxacin solutions

L.A. Goulart,a,b C. Sáez,a M.R.V. Lanza,b and M.A. Rodrigo a

a University of Castilla-La Mancha, Department of Chemical Engineering Enrique Costa Novella Building, Av. Camilo José Cela nº 12, Ciudad Real, Espan b Universidade de São Paulo (USP), Instituto de Química de São Carlos (IQSC), Av. Trabalhador São-carlense, 400 CP 780, São Carlos, SP, Brazil. [email protected]

Advanced Oxidative Processes (AOP), have demonstrated good performance for the conversion of toxic organic compounds into simple products such as CO2 and H2O, thanks to the in situ generation of hydroxyl radicals (.OH). Among them, Electrochemical oxidation appears as a good alternative for the degradation of many types of pharmaceutics. However, the efficiency of anodic oxidation is directly related to the properties of the anodes and to the reaction medium, such as the nature of raw compounds and the characteristics of the supporting electrolyte [1]. Semiconductor oxides are generally used as anodes due to their high chemical and photochemical stability [2]. In addition, the application of a fixed potential under light irradiation can decrease both the recombination of photogenerated charges in semiconductors and increase the lifetime of the electron pair, resulting in the efficient degradation of persistent pollutants. In this context, the degradation of Levofloxacin (LFX), selected as model compound, with a titanium and ruthenium oxide (MMO) electrode electrodeposited with ZnO (MMO/ZnO) in different electrolytes was studied. The influence of the electrolyte solution (Na2SO4, NaCl and urine), the pH of the solution (5, 7 and 9) and incidence of UV light were evaluated. The degradation was monitored by high performance liquid chromatography (HPLC) and total organic carbon (TOC). The experiments with light (photolysis and photoelectrolysis) presented the highest degradation percentage of LFX in the different electrolytes studied. The greatest removal of TOC was observed at basic pH. This may be related to the great stability of the MMO/ZnO electrode and the easier generation of .OH radicals in a basic medium, which results in greater degradation efficiency.

References (1) Abdessamad , N. E. H.; Akrout H.; et. al., Chemosphere 2013, 1309, 93. (2) Li P.; Bao Z.; et. al., Journal of Hazardous Materials 2019, 362, 336.

Acknowledgements This work is supported by Junta de Comunidades de Castilla-La Mancha and European Union through the project SBPLY/17/180501/000396 and by Brazilian research funding agencies: CNPq (grants no 465571/2014-0, 302874/2017-8 and 427452/2018-0); FAPESP (grants #2014/50945-4,#2016/08760-2, #2019/04084-0 and 2017/10118-0) and CAPES-Finance Code 001.

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P42-Study of the ionic transfer throws separators for Zn-based batteries

J. Torres Escalonaa, J.J. Conesaa, J.P. Tafurb, A. Díaz Barriosb, F. Santosa, S. Lorcaa, A. J. Fernández Romeroa

a Grupo de Materiales Avanzados para la Producción y Almacenamiento de Energía, Universidad Politécnica de Cartagena, Aulario II, Campus de Alfonso XIII, Cartagena. b School of Chemical Science and Engineering, Yachay Tech University, Yachay City of Knowledge, 100650-Urcuqui, Ecuador [email protected]

Separator is a fundamental component of the majority of the commercial batteries. Their main functions are to allow the ionic transport to balance the ionic gradient created by redox reactions, but avoiding the electrolytes mixing, as well as preventing the contact between the anode and cathode electrodes1. Besides, gel polymer electrolytes used in “all-solid” batteries can function simultaneously as separator and electrolyte2. Although the same separator has been frequently used in different battery type, it is important to use the appropriate separator for each kind of battery. In this sense, a separator for alkaline - 2+ 2- Zn/MnO2 and Zn/air batteries must favor mainly the OH transport and avoid Zn , as Zn(OH)4 , reaching the negative electrode, which can be blocked prematurely2. However, ZABs need Zn2+ cations to come across the separator, similar to Li+ transport in LIBs. In this work we have used a two-compartment cell to analyze the ionic transport trough the seprarators occurring during the charge/discharge cycles of a Zn-based battery. Zn electrode was immersed in a ZnO 0.4M + KOH xM solution in the left compartment, whereas xM KOH solution was used in the positive electrode compartment. These experiments were carried out using different KOH concentrations. After cycling the battery, the ionic species concentrations of each solution have been analyzed by ICP-OES technique. A high number of different membranes have been tested including commercial ones such as Nafion or Cellophane. The results obtained have been compared with the homemade prepared ones based on PVA, VAVTD, Chitosan, etc.

References:

[1] N. Vatistas, M. Bartolozzi, Journal of Power Sources 1999, 79, 199–204. [2] F. Santos, J. P. Tafur, J. Abad, A. J. Fernández Romero, Journal of Electroanalytical Chemistry 2019, 850, 113380.

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P43-Glucose sensor using platinum nanoparticles electrodeposited on a poly(Azure A) film upon activated screen printed carbon electrodes

María Isabel González Sáncheza, Francisco Jiménez Fiérreza, Rebeca Jiménez Péreza, Jesús Iniestab and Edelmira Valeroa

aDepartment of Physical Chemistry, Higher Technical School of Industrial Engineering, University of Castilla-La Mancha, Campus Universitario s/n, 02071, Albacete, Spain. bDepartment of Physical Chemistry and Institute of Electrochemistry, University of Alicante, 03690, San Vicente del Raspeig, Alicante, Spain. [email protected]

Glucose analysis is very important and common mainly because of the disease Diabetes mellitus, produced by an abnormal glucose concentration in blood and tissues, is suffered by approximately 150 million people around the world. Furthermore, the quantification of glucose is not only important in clinical analysis, but also in other areas such as food production or quality control, making essential the development of new analytical methods for the determination of this biomolecule. Electrochemical sensors are good candidates for that purpose since they offer multiple advantages such as simplicity, accuracy, portability and possibility of miniaturization.1 In this communication, a novel glucose biosensor based on glucose oxidase immobilized upon platinum nanoparticles electrodeposited on a poly(Azure A) film previously electropolymerized on activated screen printed carbon electrodes2 (SPCE) is developed. Surface characterization was performed by Field Emission-SEM, XPS and impedance measurements. Glucose measurement is based on its oxidation by the enzyme glucose oxidase by producing H2O2, which is quickly detected by anodic amperometry at +0.2 V (vs Ag as pseudo-reference electrode). Most importantly, glucose detection was performed at a low potential, which is lower than those mostly used for glucose sensors based on H2O2 electrooxidation and, therefore, may avoid some interferences. The biosensor showed an excellent sensitivity of 42.7 AmM-1cm-2, a limit of detection of 7.6 M, a linear range between 20 M and 2.3 mM and high selectivity towards glucose determination. In addition, the electrode depicted a repeatability of 3.96 % and a reproducibility of 4.76%. The biosensor was successfully applied to glucose quantification in certain commercial juices exhibiting good precision when compared with a classical spectrophotometric method. This biosensor can be easily prepared and opens up a good alternative for the development of new highly sensitive glucose sensors.

(1) Heller, A.; Feldman, B. Chemical Reviews. 2008, 108, 2482-2505. (2) Jiménez-Pérez, R.; González-Rodríguez, J.; González-Sánchez, M.-I.; Gómez- Monedero, B.; Valero, E. Sensors Actuators B Chem. 2019, 298, 126878.

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P44-Spectroelectrochemistry of phenazine-phenothiazine copolymers

F. Vicente, P. Rodenas, J. Agrisuelas, J. J. García-Jareño and E. Guillén

Departament de Química Física, Universitat de València. C/ Dr. Moliner, 50, 46100, Burjassot, València, Spain [email protected]

Phenazines and phenothiazines have been used in a wide field of technological applications, such as sensors, biosensors, organic light-emitting diodes, batteries or corrosion protection. Electrochemical reactions involving ions and water transfers occurs simultaneously with color changes1. Copolymerization of this kind of dyes open new research perspectives2. The electrochemistry of copolymers depends on monomers involved (Figure 1). Phenazines as the Neutral Red (NR) and phenothiazines as the Azure A (AA), Methylene Blue (MB) or Methylene Green (MG) were copolymerized on indium tin oxide electrodes (ITO). Simultaneously, color changes of copolymers have been investigated by means of spectroelectrochemistry techniques.

Figure 1. Cyclic voltammograms of some copolymers deposited on ITO in 0.5 M KCl aqueous solution at 50 mV s1.

References (1) Agrisuelas, J.; Gabrielli, C.; García-Jareño, J. J.; Gimenez-Romero, D.; Perrot, H.; Vicente, F. Spectroelectrochemical Identification of the Active Sites for Protons and Anions Insertions into Poly-(Azure A) Thin Polymer Films. J. Phys. Chem. C 2007, 111 (38), 14230– 14237. (2) Piwowar, K.; Blacha-Grzechnik, A.; Zak, J. Electrochemical Copolymerization of Phenothiazine Derivatives for Enhanced Singlet Oxygen Generation in Oxidation of 1,5- Dihydroxynaphthalene. J. Electrochem. Soc. 2019, 166 (16), G163–G169.

Acknowledgements This work was supported by MINECO-FEDER CTQ2015-71794-R and from Excellence Network E3TECH under project CTQ2017-90659-REDT (MINECO, Spain).

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P45-Spectro-electro-gravimetry of the compactation effect on the leuco poly-(o-toluidine) conversion to the emeraldine like forms

F. Vicente, A. Ferrer, J. Agrisuelas, J. J. García-Jareño and E. Guillén

Departament de Química Física, Universitat de València. C/ Dr. Moliner, 50, 46100, Burjassot, València, Spain [email protected]

Structural and molecular properties of polymer conducting films often change with the packing 1 time (tp) . This work examines the relaxation process induced by cyclic voltammetry of poly(o- toluidine) (POT) synthesized in H2SO4 solution. Relaxation involves the transformation of films by oxidation into the conducting form (emeraldine) with simultaneous participation of counter-ion and solvent2,3. Spectro-electro-gravimetry provides useful information about the relaxation process. Protons are expulsed when the isolated polarons detected around 420 nm are oxidized. Anions are inserted during the formation of conducting polarons (detected around 840 nm) as shows the values of the F(dm/dq) function (Figure 1).

Figure 1. Mass/charge balances of the POT relaxation of packed films during 30, 1800 and 7200 s in 0.5 M H2SO4 solution.

References (1) Otero, T.; Grande, H.; Rodriguez, J. A New Model for Electrochemical Oxidation of Polypyrrole under Conformational Relaxation Control. J. Electroanal. Chem. 1995, 394 (1– 2), 211–216. (2) Agrisuelas, J.; Gabrielli, C.; García-Jareño, J. J.; Perrot, H.; Vicente, F. Kinetic and Mechanistic Aspects of a Poly(o-Toluidine)-Modified Gold Electrode. 2. Alternating Current Electrogravimetry Study in H2SO4 Solutions. J. Phys. Chem. C 2012, 116 (29), 15630–15640. (3) Agrisuelas, J.; Gabrielli, C.; García-Jareño, J. J.; Perrot, H.; Vicente, F. Effects of Anion Size on the Electrochemical Behavior of H2SO4-Structured Poly(o-Toluidine) Films. An Ac-Electrogravimetry Study in Acid Solutions. Electrochimica Acta 2014, 132, 561–573.

Acknowledgements This work was supported by MINECO-FEDER CTQ2015-71794-R and from Excellence Network E3TECH under project CTQ2017-90659-REDT (MINECO, Spain).

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P46-Assessing the Viability of Cu-MOF and its Derivatives for Advanced Electrochemical Water Treatment

Lele Zhao, Julia Garcia-Cardona, Pere L. Cabot, Enric Brillas, and Ignasi Sirés Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain [email protected]

Metal-organic frameworks (MOFs) combine two distinct parts, i.e., organic linkers and inorganic metal centers, which give rise to crystalline porous materials through self-assembly [1]. MOFs are superior to other porous materials since they show a microporous/mesoporous structure, being the porosity highly tunable. Lately, the development of heterogeneous electro- Fenton (EF) technology has attracted the attention of a substantial number of scholars, with the aim of minimizing some of the classical shortcomings shown by homogeneous EF. In particular, the pH range may be extended without enhancing the iron sludge production. Therefore, highly stable heterogeneous catalysts for treating wastewater contaminated with refractory organic pollutants are under investigation. Recently, our group has described the great viability of heterogeneous EF process using Fe-containing MOFs and their derivatives [2,3]. Nonetheless, further improvement in the catalytic efficiency would be desirable. Cu, as an Earth abundant transition metal, has been considered as one of the most important iron-free catalysts to perform Fenton-like treatments [4]. Moreover, is worth assessing the potential application of Cu-MOF derivatives for two-electron oxygen reduction reaction (ORR). In this work, we used Cu(NO3)2 and benzene-1,3,5-tricarboxylic acid (BTC) as precursors to synthesize hydrated Cu3(BTC)2 [5] under different reaction conditions, as well as three pyrolyzed derivatives. These materials were have been characterized, further being employed as heterogeneous catalysts and electrocatalysts for cathodic H2O2 production and for the degradation of a pharmaceutical pollutant in an undivided cell containing an IrO2 anode and a gas-diffusion electrode (GDE). The performance of EF process as compared to electrochemical oxidation is currently under comparison using actual wastewater.

References: [1] Wang, C.C.; Li, J.R.; Lv, X.L.; Zhang, Y.Q.; Guo, G. Energy Environ. Sci. 2014, 7, 2831. [2] Ye, Z.; Padilla, J.A.; Xuriguera, E.; Beltran, J.L.; Alcaide, F.; Brillas, E.; Sirés, I. Environ. Sci. Technol. 2020, 54, 4664. [3] Ye, Z.; Schukraft, G.E.M.; L'Hermitte, A.; Xiong, Y.; Brillas, E.; Petit, C.; Sirés, I. Water Res. 2020, 184, 115986. [4] Wang, Y.; Xue, Y.; Zhang, C. Electrochim. Acta 2021, 368, 137643. [5] Schlichte, K.; Kratzke, T.; Kaskel, S. Micropor. Mesopor. Mater. 2004, 73, 81.

Acknowledgments Financial support from PID2019-109291RB-I00 (AEI, Spain), as well as the PhD scholarships awarded to L.Z. (State Scholarship Fund, CSC, China) and J.G.-C. (2020 FISDU 00005, Generalitat de Catalunya) are acknowledged.

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P47-Electrochemical multiplatform for the detection of fertility-related hormones in saliva

Beatriz Arévaloa, V. Serafína, J. F. Beltrán-Sánchezb, J. Aznar-Povedab, A. J. García- Sánchezb, J. García-Harob, S. Campuzanoa, P. Yañez-Sedeñoa and J. M. Pingarróna.

aDepartment of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, Ciudad Universitaria S/N, 28040, Madrid, Spain. bDepartment of Information and Communication Technologies (ICT), Technical University of Cartagena, ETSIT, Campus Muralla del Mar, E-30202, Cartagena, Spain. [email protected]

Fertility-related hormones are the main components that regulate the reproductive cycle, being involved in ovulation and pregnancy processes. These fertility hormones include progesterone (P4), which prepares the uterus for pregnancy,luteinizing hormone (LH), which stimulates the formation of the corpus luteum and ovulation, estradiol (E2), which acts as a growth hormone for reproductive organs and keeps the oocytes in the ovaries, and prolactin (PRL), which stimulates progesterone synthesis in the corpus luteum and milk production in mammary glands. In recent years, the determinationand quantification of these hormones in minimally invasive samples, such as saliva, to improve reproductive medicine treatments, has become particularly relevant. This communication will discuss the first amperometric immunosensor for the simultaneous and reliable determination of salivary P4, LH, E2, and PRL. The immunoplaform is based on direct competitive (P4 and E2) and sandwich (LH and PRL) assays, implemented onto functionalized magnetic microbeads (MBs). The amperometric transduction was performed upon placing the final modified MBs onto the working surfaces of 4 -electrodes SPCE arrays (SPC4Es) and applying -200 mV (vs. Ag pseudo-reference electrode) using H2O2/hydroquinone (HQ) system. Analytical and operational characteristics of the developed immunoplatform demonstrate high selectivity and sensitivity for each target hormone determination. The immunoplatform is suitable for the accurate determination of all targets in human saliva samples collected from individuals in different situations related to fertility and menopause. The results achieved were measured with a conventional potentiostat have been pioneeringly compared to those obtained using a low-cost custom designed and field-portable quadruple potentiostat (1). The proposed methodology proves to be competitive with conventional ELISA kits, requiring shorter incubation times and offering the possibility of developing a multiplexed immunoplatform to quantifyhormones at the point of care.

(1)V. Serafín et al., Sensors and Actuators B: Chemical, 2019, 299, 126934; doi: 10.1016/j.snb.2019.126934.

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P48-Study of Vanadium Electrolytes for the Integration of Flow Batteries in Thermal Applications

Sabrina Berling,a Enrique García - Quismondo,a and Jesus Palmaa

a Electrochemical Processes Unit, IMDEA Energy, Avda. Ramón de la Sagra 3, 28935, Móstoles, Madrid, Spain [email protected]

Practical RFB systems operate with electrolyte containing a vanadium concentration between 1.6 and 1.8 M and usually also employ electrolyte cooling and heating systems to maintain the temperature between 15 and 40ºC. This limits the integration of RFB systems in thermal applications that require broad temperature adaptability1–4, however, a flow battery electrolyte with lower vanadium concentration would allow a wider range of applications to be exploited.

In this work, the physicochemical and electrochemical properties of vanadium electrolytes at 0.9 M, 1.6 M, 1.8 M and 2.0 M concentration are studied in detail at a broad temperature range (5ºC – 50ºC). The results show that 0.9 M vanadium electrolytes are stable between the whole range of temperature at least for 5 months while concentrated solutions are inclined to form precipitation at certain temperatures after a couple of weeks. The vanadium concentration will largely influence the conductivity and viscosity of the electrolytes which eventually can affect the electrolyte fluid dynamics behavior inside the stack. Besides, the electrochemical properties of the diluted solutions are studied at different temperatures to evaluate kinetic and diffusion parameters as well as charge transfer processes.

These results enable us to better and more comprehensively evaluate the performance of the electrolyte changing the concentration, which will be beneficial for the rational choice of electrolyte for VRFB operation in emerging hybrid electrochemical and thermal energy storage systems.

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P49- Exploring the mechanism of alkali ion electrochemical intercalation into Schiff Bases

Elizabeth Castillo-Martínez,a,b , Jae Lee, a Gunwoo Kim, a Javier Carretero-González, a Raúl García,a Mike Hong, a Tao Liu, a Matthew Cliffe, a Dominique Wright, a Clare P. Greya

a Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, Cambridge, United Kingdom b Department of Inorganic Chemistry, Universidad Complutense de Madrid, Parque de las Ciencias, 2, 28040, Madrid, Spain [email protected]

Conjugated Schiff Bases have shown electrochemical activity both in solution [1] as well as in the solid state [2]. The voltage of reaction being in the range of -1.3 to -1.8V vs SCE [2] or 0.85V vs Na+/Na [4] has made these materials interesting for applications in solar cells [2], or as anode in alkali ion batteries, such as Na-ion [4]. Schiff bases undergo a reduction at voltages slightly higher than carboxylates, however they have the advantage that can be made into polymers, which, if they are solubilized [2,5] is an advantage for devices processability. The amount of charge stored in Schiff bases have been rationalized in terms of electrochemically active, likely coplanar, Hückel units -N=C-Ar-C=N- and -N=C-Ar-C=OO-, however the crystal structure of the active species remains unknown. In this presentation we will show a new molecule based on Schiff bases, which is electrochemically active as anode in alkali ion batteries. Its crystal structure is solved and corroborates previous assumptions regarding the role of molecular coplanarity in electrochemical activity. Additionally, diffraction and spectroscopic studies performed ex-situ on cycled electrodes helps in understanding some mechanistic aspects of the alkali ion intercalation process in these systems.

References (1) Martinet, P.; Simonet, J.; Tendil, J., C. R. Acad. Sci., Ser. C 1969, T269, 303. (2) Scott, J. W., Hura, W.H., Can, J. Chem. 1967, 45, 2375. (3) O. Thomas, O. Inganäs, M. R. Andersson, Macromolecules, 1998, 31, 2676. (4) Castillo Martínez, E.; Carretero-González, J. and Armand, M. Angew. Chem. Int. Ed., 2014, 53, 5341. (5) Fernandez-Hernandez, N., Sanchez-Fontecoba, P., Castillo–Martínez, E., Carretero-Gonzalez, J., Rojo, T., Armand, M., ChemSusChem, (2018) 11, 311. (6) Traetteberg, M., and Hilmo, I., The molecular structure of N-benzilidene aniline, J. Mol. Struct., 1978, 48, 395. (7) Castillo Martínez, E. et al, in preparation

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P50-Development of High Performing Polymer Electrolytes based on Superconcentrated Solutions

Diana Elena Ciurduc,a Nicola Boaretto,a, c Juan Pedro Fernández,b Jesús Palmaa, and Rebeca Marcillaa

a Electrochemical Processes Unit, IMDEA Energy, Avenida Ramón de la Sagra 3, 28935 Móstoles, Madrid, Spain b IMDEA Materials, Calle Eric Kandel 2, E-28906 Getafe, Madrid, Spain c Basque Research and Technology Alliance (BRTA), Centre for Cooperative Research on Alternative Energies (CIC EnergiGUNE), 01510 Vitoria-Gasteiz, Spain (Present Address) [email protected]

Impregnation of conventional organic electrolyte into a gelable polymer separator offer pronounced advantages over conventional liquid electrolyte, enabling the fabrication of lightweight and thin batteries with design flexibility, in which the risk of leakage is reduced. However, there are still problems to be solved, such as the low lithium transport number, safety issues associated to flammability of organic solvents and a narrow electrochemical window. 1 In this work, a new family of gel polymer electrolytes based on a PVDF-HFP porous matrix is presented. The commonly used organic-based electrolytes are substituted here by superconcentrated solutions aiming at improving some electrochemical properties such as the electrochemical stability, transport properties, aluminium corrosion and Li plating-stripping behavior. 2 We investigated the physiochemical and the electrochemical behavior of the gel-polymer electrolyte (GPE) formed by the porous PVDF-HFP soaked in concentrated solutions of LiTFSI salt in DMC:FEC mixtures. The ionic conductivity varies between 10-5 and 10-4 S cm-1 at room temperature and the highest value (0.19 mS cm-1) was obtained for a superconcentrated gel electrolyte with the following composition DMC: FEC : LiTFSI = 2: 1: 1 (GPE-211). In most of the cases the t+ is quite high, in particular, GPE-031 and GPE-111 exhibited values of t+ as high as of 0.40 and 0.56, respectively. The electrochemical stability window of this gel is improved with respect to non-concentrated gel electrolyte, reaching 5V. Additionally, the corrosion of aluminium current collector was suppressed due to the peculiar interactions between ions and solvents in concentrated electrolytes, as evidenced by Raman spectroscopy. Finally, Li / LFP and Li / NMC batteries were assembled with GPE-211, obtaining high capacity values of 147 mAh g-1 and 160mAh g-1 at 0.1 mA cm-2, respectively and good rate capability. 3

References (1) Magistris, A.; Quartarone, E.; Mustarelli, P.; Saito, Y.; Kataoka, Solid State Ionics 2002, 152–153, 347–354. (2) Zeng, Z.; Murugesan, V.; Han, K. S.; Jiang, X.; Cao, Y.; Xiao, L.; Ai, X.; Yang, H.; Zhang, J.-G.; Sushko, M. L.; Sushko, M. L.; Liu, J., Nat. Energy 2018, 3 (8), 674–681. (3) Ciurduc, D.E.; Boaretto, N.; Fernández-Blázquez, J.P.; Marcilla, R.; Journal of Power Sources, under revision.

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P51- Novel composite PBI membranes with graphene oxide as organic filler for the sulphur depolarized electrolysis

Sergio Diaz-Abad,a Mireya Carvela,a, Maya Mouawad b, Manuel Andres Rodrigoa and Justo Lobatoa

a Chemical Engineering Department, Faculty of Chemical Sciences and Technologies, University of Castilla-La Mancha, Ciudad Real, 13071, Spain b Civil and Environmental Engineering Department, Faculty of Engineering ESIB, St Joseph University of Beirut, Mar Roukoz, Lebanon [email protected]

Numerous ways of producing hydrogen with zero carbon emissions are being studied and developed in the recent years. One of the simplest processes is the electrolysis of water, but its high theoretical potential (1.23 V vs RHE) results in the need of a less energy consuming process for green hydrogen generation. In this context, the Hybrid Sulfur Cycle is of great interest because of the low required theoretical voltage (0.158V vs RHE) makes it suitable for large scale implementation. In this case, sulphur dioxide is used in the cathode to reduce the required oxidation potential of water according to reaction 1. The protons produced in the anode of the cell cross the proton exchange membrane to the cathode where they are recombined into Hydrogen (reaction 2). + - SO2 (g) + 2 H2O (g) → H2SO4 (aq) + 2H + 2 e (1) + - 2H + 2 e → H2 (g) (2) Most studies about this cycle were carried out at temperatures lower than 80°C with Nafion membranes. In this work, temperatures higher than 100ºC will be employed in the electrolyzer with regard to an increase in the global efficiency of the process. According to the limitations of Nafion for working at temperatures higher than 80°C, the selection of a different material for the proton exchange membrane is needed. Thus, polybenzimidazole (PBI) has been selected, among other materials, as polymer for the proton exchange membrane attending to its exceptional resistance to high temperatures and high chemical properties. Furthermore, striving for the enhance of the properties of PBI due to the extreme conditions (temperatures higher than 100ºC with high sulfuric acid concentrations), graphene oxide was employed as inorganic filler from concentrations of 1% to 7% in the casted membrane. In order to characterize the obtained membranes, mechanical test, ionic conductivity, acid doping level, chemical resistance, TGA and FTIR measurements were carried out. Also, the performance of the most promising membranes was studied in a 25 cm2 electrolyzer using platinum supported on Vulcan (40% Pt) for both anode and cathode with a platinum loading of 0.7 mgPt/cm2.

Acknowledgements

Financial support from the Junta de Comunidades de Castilla-La Mancha and the FEDER –EU Program, Project ASEPHAM. Grant number “SBPLY/17/180501/000330” is gratefully acknowledged.

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P52- Síntesis de composito de Cu2O/CuO por tratamiento térmico de películas delgadas de Cu2O y su aplicación como sensor no-enzimático de glucosa

Francisco Figueredoa, Paula Greza, Ricardo Schreblera and Cristopher Heyserb a Laboratorio de Electroquímica, Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Av. Universidad 330, Valparaíso, Chile. b Universidad Autónoma de Chile, Facultad de Ingeniería, Instituto de Ciencias Químicas Aplicadas, Núcleo de Astroquímica & Astrofísica, Av. Alemania 01090, Temuco, Chile. [email protected]

Diabetes mellitus, conocida como diabetes, es una enfermedad producida por el páncreas, donde esta genera deficiencia de insulina, resistencia a ella o ambos casos. Actualmente afecta a cerca de 350 millones de personas y según proyecciones de la Organización Mundial de la Salud (WHO) y la Federación Internacional de la Diabetes (IDF) se espera llegar a 700 millones de personas con esta enfermedad en el año 2040 (1). Una manera de controlar la enfermedad es medir los niveles de glucosa en fluidos fisiológicos donde los sensores electroquímicos generan resultados en forma sencilla, rápida, sensible y confiables. En la actualidad la gran mayoría de sensores de glucosa se basan en el uso de enzimas, tales como, glucosa oxidasa (Gox) y glucosa deshidrogenasa (GDH). No obstante, estos presentan una baja estabilidad frente a cambios de temperatura, pH del medio, etc. Debido a esto que se ha generado un interés creciente por dispositivos electroquímicos no enzimáticos. Principalmente formados a partir de óxidos metálicos, tales como Co3O4, NiO, ZnO y CuxO (2,3). Además, en la búsqueda de mejorar las propiedades electrocatalíticas de los sensores se ha estudiado la incorporación de compósitos, estas estructuras generan pares redox entre los estados de oxidación con la finalidad de obtener estructuras con mayor sensibilidad. En base a lo anterior, el presente estudio busca realizar un análisis sistemático de la detección y cuantificación de glucosa, empleando como sensor composito de Cu2O/CuO, en forma de películas delgadas. En primer lugar, se sintetizaron peliculas de Cu2O sobre sustrato de FTO, mediante un pulso de potencial a -0,565 utilizando disolución compuesta por 0,1 M de CH3COONa y 0,02 M de (CH3COO)2Cu, a pH 5,79 en atmósfera inerte. Luego se formó el composito Cu2O/CuO por oxidación térmica de la película de Cu2O en aire a 300 y 350°C por 90 minutos con rampa de temperatura de 4°C/min. Las estructuras fueron caracterizadas a través de microscopía electrónica de barrido (SEM) con detector de espectroscopía de dispersión de energía de rayos X (EDX) y difracción de rayos X (XRD). Mediciones preliminares del sensor, realizadas por voltametría de barrido lineal (LSV), a una concentración de 1 mM de glucosa en NaOH 0,1 M, muestran que el tratamiento térmico efectuado a 300 y 350°C poseen un 40 y 55%, respectivamente, de incremento en la densidad de corriente del pico de oxidación de glucosa al ser comparadas con la película de Cu2O.

References (1) Atlas de la Diabetes, IDF 2019, Novena edición, 1-180. (2) Heyser, C.; Schrebler, R.; Grez, P., Journal of Electroanalytical Chemistry 2019, 832, 189– 195. (3) Wenbin, L; Guochun, C; Xingming, Z; Yuxiang, D; Yang Q, Sensors & Actuators: B. Chemical 2020, 321, 128485.

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P53- Charge and pH effect of the adsorbed CTAB on Au(hkl) in aqueous solutions

José M. Gisbert-González,a María V. Oliver-Pardoa, Valentín Briega-Martos, a, b Francisco J. Sarabia,a Victor Climent,a Juan M. Feliu,a Enrique Herrero E.a

a Instituto de Electroquímica, Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain. b Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Egerlandstr. 3, 91058 Erlangen, Germany [email protected]

The behavior of adsorbed CTAB on Au(hkl) electrodes has been studied using electrochemical, indirect laser-induced jump temperature (ILIT), FTIR and Raman Spectroscopy experiments in different aqueous solutions. The results show that the adsorbed layer is stable in aqueous solutions in the whole potential range of study. The observed electrochemical and FTIR/Raman behavior is compatible with the formation of a membrane of CTA+ on the electrode surface with the polar amino groups in contact with the surface. For acid solutions, when the electrode charge is negative, the polar groups are attracted to the surface, so that the capacitance of the electrode is smaller than that recorded for the unmodified Au(hkl) electrode. As the charge becomes positive, the layer seems to detach from the surface and water molecules permeate through it, changing the capacitance of the electrode and giving rise to characteristic peaks in the voltammetric profile. At potentials higher than these peaks, the behavior of the electrode is comparable to that observed for the unmodified electrode except for basic solutions, where the layer protects the surface from the OH adsorption. The stability of the layer is facilitated by the incorporation of anions of the supporting electrolyte. Those anions remain on the layer even when the electrode is transferred to a different solution, as the electrochemical behavior show.

References Lipkowski J. Phys. Chem. Chem. Phys. 2010, 12, 13853-14368.

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P54- ptimization of Gold SERS substrates for vitamin B2 determination.

Sheila Hernandez, Martin Perez-Estebanez, William Cheuquepan, Lucia Garcia, Aranzazu Heras, Alvaro Colina. Department of Chemistry, Universidad de Burgos. Pza. Plaza Misael Bañuelos s/n, 09001 Burgos. Spain. [email protected]

Since its discovery, Surface enhanced Raman scattering (SERS) has attracted the attention of many research groups, mainly due to the high sensitivity that can be achieved with this phenomenon1. Raman spectroscopy has demonstrated to be one of the most useful techniques in analysis since the spectra obtained can be considered a fingerprint of the molecules studied. However, the lack of sensitivity has limited its applications in this field. This drawback can be overcome using SERS and other phenomena related to the enhancement of the Raman signal. SERS is a phenomenon that enhances the Raman signal due to the interaction of the molecule with a nanostructured surface with plasmonic properties. The reproducibility of these substrates is still a challenge. There are several methodologies to obtain SERS substrates such as chemical or electrochemical synthesis of nanostructures that can be deposited on the substrate. Nevertheless, most of them required long preparation time. One of the easiest and fastest ways to generate these substrates is the electrochemical roughening of metal electrode. When a technique as Raman spectroelectrochemistry (Raman-SEC) is used, the generation of the substrate can be made simultaneously with the Raman response, allowing the evaluation of the SERS substrate during its generation2. In this work, a new and simple strategy to generate SERS substrates based on the electrochemical roughening of gold screen-printed electrodes (Au-SPE) is presented. The methodology presented in this work help us to understand the process of gold oxidation - and the generation of gold nanostructures. The effect of the generation of [AuCl4] complex as well as the effect of the formation of gold oxides were evaluated. Besides, the different stages of the reduction of these products to generate gold nanostructures, and the influence of the presence of vitamin B2 as test molecule have proven to be key factors in the generation of sensitive and reproducible substrates. The quantification of this vitamin in a multivitamin complex is made in a fast and simple way, obtaining excellent figures of merit. The new procedure could be easily widespread to analyze other molecules.

Acknowledgements: Authors acknowledge the financial support from Ministerio de Economía, y Competitividad (Grant CTQ2017-83935-R- AEI/FEDERUE), Junta de Castilla y León (Grant BU297P18) and Ministerio de Ciencia, Innovación y Universidades (Grant RED2018- 102412-T). S.H. and M.P-E. thank Junta de Castilla y León and European Social Fund for their predoctoral fellowships. W. Ch. thanks JCyL for his postdoctoral fellowship (Grant BU297P18). References: (1) Perales-Rondon, J. V; Hernandez, S.; Martin-Yerga, D.; Fanjul-Bolado, P.; Heras, A.; Colina, A. Electrochemical Surface Oxidation Enhanced Raman Scattering. Electrochim. Acta 2018, 282, 377–383. https://doi.org/10.1016/j.electacta.2018.06.079. (2) Hernandez, S.; Perales-Rondon, J. V.; Arnaiz, A.; Perez-Estebanez, M.; Gomez, E.; Colina, A.; Heras, A. Determination of Nicotinamide in a Multivitamin Complex by Electrochemical- Surface Enhanced Raman Spectroscopy. J. Electroanal. Chem. 2020, 879, 114743.

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P55- Self-Assembled Monolayers of 6-amino-hexanethiol on polycrystalline gold electrode

Irene Humanes, Guadalupe Sánchez, Rafael Madueño, José M. Sevilla, Manuel Blázquez, Teresa Pineda

Departamento de Química Física y T.A., Universidad de Córdoba, Spain, Instituto Universitario de Nanoquímica (IUNAN), Universidad de Córdoba, Spain [email protected]

The necessity to change the properties of metal surfaces, e.g. hydrophilicity and hydrophobicity, at interfaces has led to modification of surfaces introducing terminal functional groups by following the strategy of self-assembled monolayers (SAMs).1 Within the hydrophilic groups, the amine is one of the less studied. The special characteristics of the -NH2 head group having the ability to exists as neutral and protonate forms deserve attention and constitutes an interesting example of chemical surface functionalization that is useful for derivatization to get appropriate sensing devices platforms.2 Previous studies have been focused on the determination of the surface pKa of amine groups in SAMs and significant dispersity on the values have been reported.3, 4

In this work, we have revisited the formation and characterization of a 6-amino-1-hexanethiol self-assembled monolayers on polycrystalline gold (AHT-SAM). We have studied the integrity and stability of these monolayers prepared under certain experimental conditions through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

The newly formed SAMs have also been characterized by contact angle measurements to evaluate the changes in the hydrophilicity of the surfaces as a function of the acid and base properties of the environmental conditions. Moreover, X-ray Photoelectron Spectroscopy (XPS) has been used to test the chemical composition of the SAM. The state of the amino terminal groups in the monolayer is monitored by examining the behavior of the redox probes as a function of the solution pH. Digital simulation of the CVs has allowed us to determine electron transfer rate constants and extracts some conclusions concerning electron exchange, surface charge and SAM organization.

References: 1. Love, J.C.; Estroff, L.A.; Kriebel, J.K.; Nuzzo, R.G.; Whitesides, G. M., Chem. Rev. 2005, 105, 1103-1169. 2. Dietrich, P. M.; Graf, N.; Gross, T.; Lippitz, A.; Krakert, S.; Schüpbach, B.; Terfort, A.; Unger, W. E. S., Surf. Interface Anal. 2010, 42, 1184-1187. 3. Marmisolle, W. A.; Capdevila, D. A.; de la Llave, E.; Williams, F. J.; Murgida, D. H., Langmuir 2013, 29, 5351-5359. 4. Campina, J. M.; Martins, A.; Silva, F., J. Phys. Chem. C 2007, 111, 5351-5362.

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P56-Using RepRap 3D printer technology for building a programmable, low cost syringe pump

b a,b a,b a,b a,b A.N. Martín-Gómez, C. Mozo-Mulero, J. Carbajo, J.J. Maraver, and J.D. Mozo

a Departamento de Electroquímica Aplicada, Centro Científico Tecnológico de Huelva, Universidad de Huelva, 21071 Huelva, Spain b Departamento de Ingeniería Química, Química Física y Ciencia de los Materiales, Universidad de Huelva, 21071 Huelva, Spain [email protected]

The acquisition costs of analytical instrumentation are generally restrictive and if resources needed for research are not available, as is the case in developing countries, progress becomes profoundly hampered1. The initiative to use 3D RepRap printing technology comes from the need to self-manufacture low-cost analytical equipment, capable of obtaining results comparable to those offered by commercial companies2,3. In this regard, the aim of this work is to build a low-cost syringe pump by using the mechanical parts, electronics and programming tools that have been developed around RepRap technology. We have manufactured a standalone infusion/withdrawal syringe pump that can be either remotely controlled from any computer or manually from a panel. The fact that the device was created from scratch, allows us to decide every feature that the pump will have, e.g., to program a complex flow sequence with up to 10 stages, with the possibility of Figure 1. Block diagram of the electronics of the synchronizing its operation with other prototype pump. devices (valves, other pumps, detectors, etc.). A commercial pump that includes all these features can cost over 4000€ while the pump we have manufactured cost less than 500 €. This substantial reduction in manufacturing costs is mainly due to the reuse of mechanic and electronic components, coupled with the use of Opensource software. Open-source licenses sometimes require the results obtained from the information available to be freely accessible. For this reason, our results will be available, in the near future, under the relevant Open-source license.

References (1) van Helden, P. The Cost of Research in Developing Countries. EMBO Rep. 2012, 13 (5), 395–395. (2) Bravo-Martinez, J. Open Source 3D-Printed 1000 ΜL Micropump. HardwareX 2018, 3, 110–116. (3) Lake, J. R.; Heyde, K. C.; Ruder, W. C. Low-Cost Feedback-Controlled Syringe Pressure Pumps for Microfluidics Applications. PLoS One 2017, 12 (4).

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P57-Polyaniline/thermally reduced graphene oxide nanocomposites for DA sensing

Daria Mintaa, Zoraida Gonzálezb, Adam Moyseowicza and Grażyna Gryglewicza

a Department of Process Engineering and Technology of Polymer and Carbon Materials, Faculty of Chemistry, Wrocław University of Science and Technology, Gdańska 7/9, 50-344, Wrocław, Poland; Instituto de Ciencia y Tecnología del Carbono, INCAR-CSIC, Francisco Pintado Fe 26, 33011 Oviedo, Spain; [email protected]

Nowadays, there is a great research interest on the development of electrochemical sensors able to monitor the level of substances in the human organism, for example dopamine (DA). DA is one of the most important neurotransmitters. The unproper level of DA can be indicative of several serious diseases like Parkinson and Alzheimer or long term dejection leading to depression1. Electrochemical sensors are promising due to their fast response, low- cost and ease of preparation2. However, to obtain high sensitivity and low limit of detection, different materials as working electrode modifiers are being applied. Among them reduced graphene oxide (rGO) and polyaniline (PANI) composite materials are being used1. The graphene materials and conducting polymers increase conductivity and facilitate molecules immobilization1,3. Thus, tailoring the composites properties by selecting a suitable synthesis technique is necessary. In this work, thermally reduced graphene oxides (TRGOs) obtained at different temperatures (400 and 700 ºC) were used to prepare PANI/TRGO nanocomposites via hydrothermal approach. The nanocomposites were evaluated and compared as working electrode modifiers in DA sensing. The significant differences in their morphology and chemical composition have been revealed. The distribution of PANI between the graphene layers was more homogenous for PANI/TRGO-700 compared to PANI/TRGO-400 due to higher exfoliation degree of the former. As a result, PANI/TRGO-700 exhibited an enhanced performance in electrochemical DA sensing presenting a limit of DA detection of 430 nM in the linear range between 0.8 – 20 µM.

Figure 1. SEM images of PANI/TRGO-400 (a) and PANI/TRGO-700 (b).

References: (1) Jackowska, K.; Krysinski, P. Anal. Bioanal. Chem. 2013, 405, 3753–3771 (2) Anuar, N. S.; Basirun, W. J.; Shalauddin, M.; Akhter, S. RSC Adv. 2020, 10, 17336– 17344 (3) Naveen, M. H.; Gurudatt, N. G.; Shim, Y. B. Appl. Mater. Today 2017, 9, 419–433.

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P58- Voltammetry of Reversible Electrode Reactions with Complex Stoichiometry at Electrodes and Microelectrodes

Angela Molina, Eduardo Laborda, Joaquín González, Francisco Martínez-Ortiz

Departamento de Química Física, Facultad de Química, Regional Campus of International Excellence “Campus Mare Nostrum”, Universidad de Murcia, 30100 Murcia, Spain [email protected]

In this communication, a general theory is presented for a reversible electron transfer reaction with complex stoichiometry, specifically, 2:1, 1:2, 3:1 or 1:3. Among other experimental systems, the case 2:1 has been reported to describe satisfactorily the hydrogen evolution from protons at platinum in aqueous media and from hydride ions in molten salts 1, the 1:2 case corresponding to the electro-oxidation/reduction of H2, the 3:1 stoichiometry of the electro-oxidation of halide anions 2 and the a:1 case (a=1,2,3,4) of the electro-oxidation of mercury in complexing media 3. A general explicit analytical solution is deduced in this work to investigate the response of electrode reactions of nonunity stoichiometry in any voltammetry technique, from normal pulse voltammetry to cyclic voltammetry (CV), and at electrodes of any size and shape. The cyclic voltammograms of the 2:1, 1:2, 3:1 and 1:3 stoichiometries are analyzed comprehensively under transient and steady state conditions, revealing the existence of an isopoint (that is, a crossing point between voltammograms obtained at different scan rates) at microdiscs and micro(hemi)spheres (see Figure 1), the features of which can assist the experimental determination of stoichiometric coefficients (or the formal potential). Also, the peak current, the peak-to-peak separation and the shape of transient CV curves, as well as the slope of the stationary current-potential response, depend on the reaction stoichiometry. Based on this, simple diagnosis criteria are proposed.

Spherical v (mV/s)X Data= 103 Disc v (mV/s) = 103 0.6 0.6

0.4 0.4 2 102 10 <1 0.2 <1 0.2

iso, disc (= 0.224) iso, sph (= 0.17)

(a.u.) 0.0 (a.u.) 0.0  

-0.2 -0.2

-0.4 Eiso,sph (= E1/2 - 0.037) -0.4 Eiso,disc (= E1/2 - 0.04)

0.2 0.1 0.0 -0.1 -0.2 0.2 0.1 0.0 -0.1 -0.2 E - E / V E - E / V 1/2 1/2 Figure 1. Cyclic voltammetry of the 2:1 stoichiometry with n=2 at (hemi)spherical and disc 4 electrodes of radius r0= 25 µm .

Acknowledgements Fundación Séneca - Agencia de Ciencia y Tecnología Región de Murcia (19887/GERM/15).

References (1) Kätelhön, E.; Batchelor-McAuley, C.; Compton, R. G., J. Phys. Chem. C 2015, 119, 23203. (2) Bennett, B.; Chang, J.; Bard, A. J., Electrochim. Acta 2016, 219, 1. (3) Jaworski, A.; Stojek, Z.; Osteryoung, J. G., J. Electroanal. Chem. 2003, 558, 141. (4) Laborda, E.; Gonzalez, J.; Martinez-Ortiz, F.; Molina, A. J. Electroanal. Chem. 2020.

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P59-Manufacture of Electrochemical Sensors based on CNT modified electrodes and mediating nitro-compounds

C. Mozo-Mulero a,b, A.N. Martín-Gómeza, J. D. Mozoa,b, J. J. Maraver a,b, J.Carbajoa,b

a Departamento de Ingeniería Química, Química Física y Ciencia de los Materiales, Universidad de Huelva, Av. 3 de Marzo s/n, 21071 Huelva, Spain. b Departmento de Electroquímica Aplicada, Centro Científico Tecnológico de Huelva, Universidad de Huelva, 21071 Huelva, Spain. [email protected]

The different materials formed from carbon atoms have always been of great interest for the construction of electrodes, but with the discovery of carbon nanotubes (CNT), a real revolution in electrodical materials began. One of the most used method to prepare CNT modified electrodes easily and quickly is to put a few microlitres of a CNT suspension on a glassy carbon electrode (GCE) and then evaporate the solvent. The use of such CNT modified electrodes increase the adsorption capacity of certain compounds, that can be used as redox mediator1. The bibliographical background indicates that the compounds with the highest adsorption capacity in the CNT network are those of an aromatic nature, due to the - type interactions that systems present2. The 70 influence on the adsorption of 60 carbonylic aromatic compounds of different sizes and 50 geometries has been 3 40 previously studied .

30 The research proposed in this 20 abstract is to analyze the influence of the molecular structure of some 10 reagents, having the same structure 0 and including the nitro moiety at 5 10 15 20 25 30 35 40 different places and amounts. 1 /Ce (103 M ‐ 1 ) Figure 1. Langmuir Isoterm of several nitroquinolinic compounds.

References (1) Mano, N.; Kuhn, A. Immobilized Nitro-Fluorenone Derivatives as Electrocatalysts for NADH Oxidation. J. Electroanal. Chem. 1999, 477 (1), 79–88. https://doi.org/10.1016/S0022-0728(99)00393-9. (2) Ahumada, J. A. E. R. U. “ Estudios Electroquímicos En Nitrocompuestos Encapsulados En Nanotubos de Carbono,” Universidad de Chile, 2017. (3) J. Carbajo, E. Gutiérrez-Álvarez, J. J. Maraver, J. D. M. Adsorción de Compuestos Quinolínicos Sobre Nanotubos de Carbono de Pared Multiple (MWCNT). Estudios Espectroscópicos Y Electroquímicos | Request PDF. In 38 GE-RSEQ / 19 EIB; Vitoria- Gasteiz (Spain), 2017.

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P60-Dual electrochemical immunoplatform for the determination of PD-L1 and HIF-1α: biomarkers of tumor hypoxia and metastasis

Cristina Muñoz-San Martín,a Maria Gamella, a María Pedrero, a Ana Montero-Calle, b Víctor Pérez-Ginés, a Jordi Camps, c Meritxell Arenas, c Rodrigo Barderas, b Susana Campuzano, a José M. Pingarrón a

a Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040, Madrid, Spain b UFIEC, Chronic Disease Programme, Instituto de Salud Carlos III, Majadahonda, 28220, Madrid, Spain c Unitat de Recerca Biomèdica, Hospital Universitari Sant Joan, Institut d’Investigació Sanitària Pere Virgili, Universitat Rovirai Virgili, 43204, Reus, Spain [email protected]

Hypoxia is considered a driving force of cancer development, invasion and metastasis. Tumor cells can adapt to this reduced oxygen microenvironment by expressing hypoxia inducible factor 1α (HIF-1α) protein, which is a major transcription factor involved in the activation of numerous genes implicated in the pathogenesis of cancer. Recently, several studies have shown that HIF-1α promotes the expression of programmed death ligand 1 (PD-L1), an immune checkpoint involved in the suppression of T-cell function and the restriction of tumor cell killing leading to cancer progression. Both proteins, PD-L1 and HIF-1α, are upregulated under hypoxic conditions in a variety of human cancers and their simultaneous blockade may represent a novel therapeutic approach for cancer immunotherapy. These features make these two proteins relevant biomarkers of tumor progression, their simultaneous determination being decisive for controlling patient’s condition and therapies efficiency. Within this context, in this communication we will present the most relevant results obtained in the development of the first dual immunoplatform developed so far for the accurate determination of these emerging cancer biomarkers of great relevance. The developed biosensor is based on the immobilization of specific capture antibodies onto activated carboxylic-magnetic beads, and the selective capturing and sandwiching of the target proteins with the corresponding biotinylated detector antibodies further conjugated with a streptavidin- HRP complex. The extension of the affinity reactions is carried out by amperometry at screen- printed dual carbon electrodes using the hydroquinone (HQ)/HRP/H2O2 system (1). Under the optimal experimental conditions, the developed dual immunoplatform offers a great analytical performance in terms of reproducibility, low detection limits, analysis time, selectivity against other proteins usually found in biological samples, and stability within time of the prepared and stored capture antibody magneto-immunoconjugates. Moreover, the applicability of this bioplatform is demonstrated through the determination of both biomarkers in cell lysates, using only 0.5 µg of these complex samples for the analysis. All these features, along with the simplicity of the protocol, the portability potential of the measuring system, and the possibility to perform the determination within clinically actionable times, make this biotool particularly appealing for incorporation into the oncology routine. (1) Muñoz-San Martín, C.; Gamella, M.; Pedrero, M.; Montero-Calle, A.; Pérez-Ginés, V.; Camps, J.; Arenas, M.; Barderas, R.; Campuzano, S.; Pingarrón, J.M. Analytical and Bioanalytical Chemistry 2021; https://doi.org/10.1007/s00216-021-03240-8.

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P61- Increasing conductivity of iron fluorides for Li-ion battery applications

B. Guitián,a X. R. Nóvoa,a A. Pintosa

a University of Vigo, EEI, ENCOMAT Group. Campus Universitario, 36310 Vigo, Spain [email protected]

The Li-ion batteries sector plays one of the most important roles in the field of energy storage. LiBs are widely used as power sources both for consumer electronics and electric vehicles. However, answering the great demand for higher energy storage capacity with low weight and low cost is still their shortcoming. Currently, the reaction mechanism in both electrodes of LiBs, the anode and the cathode; involves insertion reactions. The cathode material and the electrical contact between active material and the current collector still represent the main limitation for the cell capacity increasing. Directly grown layers of the active material on the current collector decreases ohmic resistance and increases the available charge. This guarantees good electrical contact and it is possible to increase the nominal capacitance if the active material is able to work under conversion reaction conditions. The electrode material will reach through all its entire range of oxidation states. Transition metal fluorides, such as FeF3, provide high nominal capacity. Therefore, they are good candidates to the conversion reactions with lithium ions [1, 2]. Direct formation of a fluoride based layer has been achieved by anodizing iron strips in ethylene glycol and NH4F as electrolyte, resulting a highly nanoporous layer of a mixture of iron oxyhidroxifluorides [3]. Nevertheless, the main limitation of those fluoride layers is its poor electronic conductivity, which affect to their performance as electroactive material. The present work focuses on developing a FeF3 conversion layer on different ferrous materials with different carbon content with the aim of decreasing costs and improving the electronic conductivity of the layers synthesized as in [3] due to the presence of carbon. The results show that the higher the content of carbon in the matrix, the higher the conductivity and the better its electrochemical properties.

Keywords: Li-ion batteries, electronic conductivity, iron fluorides

References [1] Badway, F.; Cosandey, F.; Pereira, N.; Amatucci, G. G. Carbon Metal Fluoride Nanocomposites. J. Electrochem. Soc., 2003, 150 (10), A1318. https://doi.org/10.1149/1.1602454. [2] Badway, F.; Pereira, N.; Cosandey, F.; Amatucci, G. G. Carbon-Metal Fluoride Nanocomposites. J. Electrochem. Soc., 2003, 150 (9), A1209. https://doi.org/10.1149/1.1596162. [3] Guitián, B.; Lascaud, S.; Nóvoa, X. R.; Ribeaucourt, L.; Vidal, E. On the Growth of Nanostructured Iron Hydroxy-Fluorides for Li-Ion Batteries. J. Power Sources, 2013, 241, 567–571. https://doi.org/10.1016/j.jpowsour.2013.04.145.

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P62- Electrochemical Biosensor for Simultaneous Determination of Rheumatoid Factor and Anti-Cyclic Citrullinated Peptide Antibodies

Esther Sánchez-Tirado, Sara Guerrero, Gonzalo Martínez-García, Araceli González-Cortés, María Lourdes Agüí, Paloma Yáñez-Sedeño and José Manuel Pingarrón

a Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, Avda. Complutense s/n 28040 Madrid, Spain [email protected]

In the serum of rheumatoid arthritis patients is frequent occurrence of autoantibodies, being the most important IgM-rheumatoid factor (RF) and anti-citrullinated protein antibodies (CPAs), which play an important role in inducing inflammation and joint damage, releasing pro-inflammatory cytokines from monocytes and macrophages (1). In this work, a dual biosensor for the simultaneous determination of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCPA) antibodies used as biomarkers for detection of rheumatoid arthritis autoimmune disease is described. The optimized methodology involves the preparation of sandwich-type biosensors with Fc fragments of IgG (Fc(IgG)) captured onto HOOC-MBs for immobilization of RF, and biotinylated- cyclic cytrullinated peptide (CCP-Biotin) to form CCP-Biotin-Neutravidin-MBs for the specific immobilization of CCPA, followed by the conjugation with the respective HRP-labeled antibodies (HRP-IgM for RF, and HRP-IgG for CCPA). Electrochemical detection was performed by amperometry at - 0.20 V vs. Ag pseudo-reference electrode using the H2O2/HQ system. The dual biosensor exhibited high sensitivities for RF and CCPA with LOD values of 0.8 IUꞏmL-1 and 2.5 IUꞏmL-1, respectively. Moreover, the simultaneous determination can be completed in about two hours, applying a simple protocol and a sample volume four times lower than that required by the ELISA method. Good results were obtained by application of the dual biosensor to the determination of both targets in human serum.

Figure 1. Schematic display of the preparation and functioning of the dual biosensor

References (1) Bos, W.H.; Wolbink, G.J.; Boers, M.; Tijhuis, G.J.; de Vries, N.; van der Horst-Bruinsma; Tak, P.P.; van de Stadt R.J., van der Laken, C.J.; Dijkmans, B.A.C.; van Schaardenburg, D. Ann. Rheum. Dis. 2010, 69, 490–494.

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P63- Interfacial studies of d-metals modified Pt single crystal surfaces. Effect on pzfc, HER and CO oxidation.

Francisco J. Sarabia Víctor Climent and Juan M. Feliu

Departamento de Química-Física and Instituto de Electroquímica, Universidad de Alicante, Apdo. 99. 03080, Alicante, Spain [email protected] Energy consumption is expected to increase severely in the coming years, linked to worldwide economic and technological development. In this regard, there is great interest in the so-called “hydrogen economy”, which uses hydrogen as an energy vector. Fuel cells and electrolysers play a fundamental role in this context. For this reason, the development of new materials to obtain efficient electrocatalysts is very important. Ni/Pt alloys have been proposed as one of the best catalysts for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR).1 In addition, different descriptors for the HER have been postulated, such as the binding energies (Subbaraman et. al) or the reorganization energy of interfacial water structures (Ledezma et. al)2. In this work, the effect on HER of modification of platinum single crystal electrodes by d-metals (Ni, Fe and Co) deposition has been studied based on the proposal of the water structure reorganization using the laser induced temperature jump technique to determine the potential of maximum entropy (pme).3 The displacement of the pme towards the onset of HER decreases the reorganization energy and increases the rate of the reaction. The bimetallic electrode-solution interface was characterized with cyclic voltammetry, CO displacement and FTIRRAS. Detailed coulometric measurements, combined with the results of the CO displacement experiment, allow determination of stoichiometric relationships and coverage calculations. Stepped surfaces decorated with adatoms serve to create ordered patterns on the surface that allow a systematic study on their catalytic effect.

0 Figure 1. A) Cyclic voltammograms of the Pt(775) surface modified with Ni(OH)2 (dashed line) and without nickel (full line), and B) the same showing the hydrogen evolution reaction. 0,1 M NaOH (pH 13). 50mV/s. Ohmic resistance was corrected in B)

References (1) Subbaraman, R.; Tripkovic, D.; Strmcnik, D.; Chang, K.-C.; Uchimura, M.; Paulikas, A. P.; Stamenkovic, V.; Markovic, N. M. Science 2011, 334, 1256−1260. (2) Ledezma-Yanez, I.; Wallace, W. D. Z.; Sebastián-Pascual, P.; Climent, V.; Feliu, J. M.; Koper, M. T. M. Nat. Energy 2017, 2 (4), 17031-17037. (3) Garcia-Araez, N.; Climent, V.; Feliu, J. J. Phys. Chem. C 2009, 113 9290-9304.

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Current Trends in Electrochemistry 6 - 9 July 2021 Paris, France

P64- Optimization of zinc phosphate coatings on high strength steel: influence of the pickling acid

B. Díaz, X. R. Nóvoa, C. Pérez, B. M. Prieto, S. Silva,

Encomat Group, University of Vigo, Campus As Lagoas-Marcosende, 36310 Vigo, Spain [email protected]

The phosphating process can be defined as a metal surface treatment to generate a coating with corrosion protection ability. Phosphating is based on a chemical conversion reaction that transforms the surface of the metallic substrate into a non-metallic crystalline layer, composed of insoluble phosphate salts highly adherent to the metal base.

Zinc phosphate coatings are commonly used as a base layer of lubricant and as primers for painting. This type of phosphating stands out in terms of chemical stability and lasting corrosion protection1.

The phosphating process involves several steps being the prior surface finishing crucial to the phosphating stage. Thus, in order to obtain a high-quality phosphate film with good adhesion, the metal pieces must be acid pickled. This stage is necessary to dissolve and remove the oxides that originated in the metal manufacturing processes and to provide a clean surface where the film can be further developed.

The main objective of this study is to test the influence of different types of acids used in the pickling process on the coating characteristics. Thus, solutions of citric acid, hydrochloric acid, sulfuric acid, and phosphoric acid have been analyzed. The variables that have been considered were the concentration of the acids, the immersion time, and the pickling bath temperature. The work was mainly focused on the study of citric acid as an alternative pickling agent. It is a not-expensive organic acid and the eventual vapors released during the pickling process are not harmful to the environment. Moreover, the handling of this acid does not involve a serious risk for the staff.

The characterization of the phosphating coatings has been completed by surface analysis, specifically SEM, and electrochemical techniques, such as EIS and linear sweep polarization.

References (1) Díaz, B.; Freire, L.; Mojío, M.; Nóvoa, X. R. Optimization of Conversion Coatings Based on Zinc Phosphate on High Strength Steels, with Enhanced Barrier Properties. J. Electroanal. Chem. 2015, 737, 174–183.

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P65- Corrosion Inhibition of Copper in 3.5 wt.% Sodium Chloride Solution by 5-(4-Pyridyl)-1,3,4-oxadiazole-2-thiol

Simona Varvara,a Camelia Berghian-Grosan,b Roxana Bostan,a Raluca Lucacel Ciceo,c Zohreh Salarvand,d Milad Talebian,e Keyvan Raeissi,e Javier Izquierdo,f Ricardo M. Soutof

a Department of Cadastre, Civil Engineering and Environmental Engineering, “1 Decembrie 1918” University of Alba Iulia, 15-17 Unirii St., 510009 Alba-Iulia, Romania b National Institute for Research and Development of Isotopic and Molecular Technologies, Donat 67-103, 400293 Cluj-Napoca, Romania c Faculty of Physics, Babes-Bolyai University, Cluj-Napoca, Romania. Interdisciplinary Research Institute on Bio-Nano-Science, Babes-Bolyai University, Cluj-Napoca, Romania d Department of Chemistry, Chemistry and Petrochemistry Research Center, Standard Research Institute (SRI), Karaj 31747-34563, Iran e Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156- 83111, Iran f Institute of Materials and Nanotechnology, Universidad de La Laguna, P.O. Box 456, E- 38200 La Laguna (Tenerife), Spain [email protected]

This work reports on the inhibitive proprieties of 5-(4-Pyridyl)-1,3,4-oxadiazole-2-thiol (PyODT) on copper corrosion in 3.5wt.% NaCl, using a multiscale electrochemical approach, surface analytical techniques (SEM-EDX, Raman and XPS), quantum chemical calculations and molecular dynamics simulations. A machine learning method based on the Raman results was also applied in an attempt to follow the evolution of the adsorbed inhibitor film on the metal. The work brings an important advance in the field taking into consideration that PyODT was proved to be an excellent corrosion inhibitor of copper by electrochemical evaluation using EIS, potentiodynamic and the scanning vibrating electrode technique (SVET), reaching efficiencies higher than 99%, at a concentration of 1.5 mM, after 24 hours of exposure to the corrosive medium. Surface microscopy inspection and spectroscopy analysis by Raman, SEM-EDX and XPS reveals the formation of a compact inhibitor film responsible for the long-lasting anticorrosive protection to the metal (168 hours). Quantum Chemistry calculations in aqueous solution and Molecular Dynamic study predict strong interaction between copper and the thiolate group, resulting in planar configuration and extensive coverage of metal surface, responsible for the excellent corrosion protection. The main interaction between the copper and PyODT proceeds through the thiolate and oxadiazole groups.

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P66-SHINe a Light on Electrochemical Reactions

Julia Fernández Vidala, Thomas A. Gallowaya, Ana M. Gómez Marínb, Gary A. Attardc and Laurence J. Hardwicka aStephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK. bInstituto de Quimica de São Carlos, Universidade de São Paulo, São Paulo, 13560-970. cDepartment of Physics, University of Liverpool, UK. [email protected]

The study of the mechanism of oxygen reduction and evolution reactions (ORR and OER) in non-aqueous solvents is of great importance, especially for the evolvement of metal-air batteries.1 The direct operando monitoring of surface reactions at Pt{hkl} electrodes can provide further insight of the redox processes taking place at the electrochemical interface.2 Shell-Isolated Nanoparticles for Enhanced Raman Spectroscopy (SHINERS)3 is a nondestructive, powerful technique for surface analysis that overcome the limitations of Surface Enhanced Raman Spectroscopy (SERS) and can be used to investigate and identify chemical species on any electrodes.4,5 SHINERS consist of a core made of metals with Surface Plasmon Resonance (SPR) properties in the visible region covered with a thin (2-3 nm), chemically inert shell that isolates the core to eliminate any interference from the metal surface. The relevance of the shell material choice is considered in this work and emphasis has been attracted on tin (IV) dioxide-coated nanoparticles. Likewise, Raman spectroscopy and electrochemistry (EC-SHINERS) results on electrified interfaces and different surfaces in operando conditions are discussed, with particular focus on oxygen reactions in aprotic solvents on Pt electrodes.

(1) Aldous, I. M.; Hardwick, L. J. Influence of Tetraalkylammonium Cation Chain Length on Gold and Glassy Carbon Electrode Interfaces for Alkali Metal-Oxygen Batteries. J. Phys. Chem. Lett. 2014, 5 (21), 3924–3930. (2) Galloway, T. A.; Dong, J.-C.; Li, J.-F.; Attard, G.; Hardwick, L. J. Oxygen Reactions on Pt{hkl} in a Non-Aqueous Na+ Electrolyte: Site Selective Stabilisation of a Sodium Peroxy Species. Chem. Sci. 2019, 10, 2956–2964. (3) Li, J. F.; Huang, Y. F.; Ding, Y.; Yang, Z. L.; Li, S. B.; Zhou, X. S.; Fan, F. R.; Zhang, W.; Zhou, Z. Y.; Wu, D. Y.; et al. Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy. Nature 2010, 464 (7287), 392–395. (4) Dong, J. C.; Zhang, X. G.; Briega-Martos, V.; Jin, X.; Yang, J.; Chen, S.; Yang, Z. L.; Wu, D. Y.; Feliu, J. M.; Williams, C. T.; et al. In Situ Raman Spectroscopic Evidence for Oxygen Reduction Reaction Intermediates at Platinum Single-Crystal Surfaces. Nat. Energy 2019, 4 (1), 60–67. (5) Galloway, T. A.; Hardwick, L. J. Utilizing in Situ Electrochemical SHINERS for Oxygen Reduction Reaction Studies in Aprotic Electrolytes. J. Phys. Chem. Lett. 2016, 7 (11), 2119–2124.

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Current Trends in Electrochemistry 41st Meeting of the Electrochemisty Group of the Spanish Royal Society of Chemistry 1st French‐Spanish Atelier/Workshop on Electrochemistry

Paris 6th July – 9th July 2021

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