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Electrocatalyst Development for PEM Water Electrolysis and DMFC: Towards the Methanol Economy

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Electrocatalyst Development for PEM Water Electrolysis and DMFC: Towards the Methanol Economy Electrocatalyst development for PEM water electrolysis and DMFC: towards the methanol economy Radostina Vasileva Genova-Koleva ADVERTIMENT. La consulta d’aquesta tesi queda condicionada a l’acceptació de les següents condicions d'ús: La difusió d’aquesta tesi per mitjà del servei TDX (www.tdx.cat) i a través del Dipòsit Digital de la UB (diposit.ub.edu) ha estat autoritzada pels titulars dels drets de propietat intel·lectual únicament per a usos privats emmarcats en activitats d’investigació i docència. No s’autoritza la seva reproducció amb finalitats de lucre ni la seva difusió i posada a disposició des d’un lloc aliè al servei TDX ni al Dipòsit Digital de la UB. No s’autoritza la presentació del seu contingut en una finestra o marc aliè a TDX o al Dipòsit Digital de la UB (framing). Aquesta reserva de drets afecta tant al resum de presentació de la tesi com als seus continguts. En la utilització o cita de parts de la tesi és obligat indicar el nom de la persona autora. ADVERTENCIA. La consulta de esta tesis queda condicionada a la aceptación de las siguientes condiciones de uso: La difusión de esta tesis por medio del servicio TDR (www.tdx.cat) y a través del Repositorio Digital de la UB (diposit.ub.edu) ha sido autorizada por los titulares de los derechos de propiedad intelectual únicamente para usos privados enmarcados en actividades de investigación y docencia. No se autoriza su reproducción con finalidades de lucro ni su difusión y puesta a disposición desde un sitio ajeno al servicio TDR o al Repositorio Digital de la UB. No se autoriza la presentación de su contenido en una ventana o marco ajeno a TDR o al Repositorio Digital de la UB (framing). Esta reserva de derechos afecta tanto al resumen de presentación de la tesis como a sus contenidos. En la utilización o cita de partes de la tesis es obligado indicar el nombre de la persona autora. WARNING. On having consulted this thesis you’re accepting the following use conditions: Spreading this thesis by the TDX (www.tdx.cat) service and by the UB Digital Repository (diposit.ub.edu) has been authorized by the titular of the intellectual property rights only for private uses placed in investigation and teaching activities. Reproduction with lucrative aims is not authorized nor its spreading and availability from a site foreign to the TDX service or to the UB Digital Repository. Introducing its content in a window or frame foreign to the TDX service or to the UB Digital Repository is not authorized (framing). Those rights affect to the presentation summary of the thesis as well as to its contents. In the using or citation of parts of the thesis it’s obliged to indicate the name of the author. Programa de Doctorat: ELECTROQUÍMICA. CIÈNCIA I TECNOLOGIA Departament de Ciència de Materials i Química Física Secció de Química Física ELECTROCATALYST DEVELOPMENT FOR PEM WATER ELECTROLYSIS AND DMFC: TOWARDS THE METHANOL ECONOMY Tesi que presenta Radostina Vasileva Genova-Koleva per optar al títol de Doctor per la Universitat de Barcelona Directors de tesi: Dr. Pere Lluís Cabot Julià Dr. Francisco Alcaide Monterrubio Catedràtic de Química Física Investigador Principal Universitat de Barcelona Fundación CIDETEC Tutor: Dr. Enric Brillas Coso Catedràtic de Química Física Universitat de Barcelona Laboratori d’Electroquímica de Materials i del Medi Ambient Dr. PERE-LLUÍS CABOT i JULIÀ, Catedràtic del Departament de Ciència de Materials i Química Física de la Facultat de Química de la Universitat de Barcelona i Dr. FRANCISCO ALCAIDE MONTERRUBIO, Investigador Principal de la División de Energía d’IK4- CIDETEC, CERTIFIQUEN: Que el present treball de recerca, que porta per títol “Electrocatalyst development for PEM water electrolysis and DMFC: Towards the methanol economy”, constitueix la memòria presentada per Radostina Vasileva Genova-Koleva per optar al grau de Doctor per la Universitat de Barcelona, i ha estat realitzat sota la nostra direcció en el marc del Programa de Doctorat “Electroquímica. Ciència i Tecnologia”, preferentment als laboratoris de Fundación CIDETEC, en col·laboració amb el Laboratori d’Electroquímica dels Materials i del Medi Ambient del Departament de Ciència de Materials i Química Física de la Universitat de Barcelona. I per tal de deixar-ne constància, signem el present certificat a Barcelona, sis de juny de dos mil disset. ACKNOWLEDGEMENTS First of all I would like to acknowledge my supervisors, Prof. Pere Lluis Cabot and Dr. Francisco Alcaide Monterrubio for their enormous help, support and guidance during the entire process of research and administrative issues related to this PhD thesis. My special thanks goes to my colleagues and my office-mates in IK4-CIDETEC Dr. Garbiñe Álvarez and Eng. Amaia Querejeta for their willing assisting me when help was needed, for their support, enthusiasm and useful discussions and advices, for helping with practical and administrative issues. My thanks also go out to the support I received from the collaborative work at the ICGM-CNRS, University of Montpellier 2, to Prof. Deborah Jones for her invitation and supervision of my secondment and to Dr. Julia Savych for her help to measurements performed there. I would like to thank to Initial Training Network, SUSHGEN, funded by the FP7 Marie Curie Actions of the European Commission (FP7-PEOPLE-ITN-2008-238678), for the financial support. Finally, I would like to thank my family for their love and support. Contents Abstract 1 Resumen 7 1.Introduction 27 1.1. Water electrolysis 35 1.2 Basic principles of water electrolysis. Theory 39 1.2.1 Thermodynamics 39 1.2.2 Kinetics 42 1.3 Proton Exchange Membrane Water Electrolysis (PEMWE). Literature review 45 1.3.1 Bipolar Plates 45 1.3.2 Gas Diffusion Layer 47 1.3.3 Solid Polymer Electrolyte Membrane 49 1.3.4 Electrocatalysts for the hydrogen evolution reaction (HER) 51 1.3.5 Electrocatalysts for the oxygen evolution reaction (OER) 53 1.3.6 Supports for thehydrogen evolution (HER) and the oxygen evolution reaction (OER) catalysts 57 1.3.7 MEA formulation and performance 60 1.4 Basic principles of DMFC. Theory 67 1.4.1 Thermodynamics 67 1.4.2 Kinetics 69 1.5 DMFC catalysts. Literature review 73 1.5.1 Electrocatalysts for the oxygen reduction reaction (ORR) 75 1.5.2 Electrocatalysts for the methanol electrooxidation reaction (MOR) 76 1.5.3 Supports for the electrocatalysts in DMFC 77 1.5.4 MEAs for DMFC 79 2. Thesis objectives 83 3. Methodology 85 3.1 Synthesis of the materials 85 3.1.1 Synthesis of the TiO2 and Nb-doped TiO2 supports 85 3.1.2 Synthesis of the TNT and Nb-doped TNT supports 85 3.1.3 Synthesis of Pt catalysts 86 3.1.4 Synthesis of IrO2 and IrRuOx catalysts 86 3.2 Physico-chemical characterization of the PEMWE materials 87 3.3 Electrochemical characterization of the PEMWE materials 91 3.3.1 Experimental setup 91 3.3.2 Electrode preparation and characterization of the HER catalysts 92 3.3.3 Electrode preparation and characterization of the OER catalysts 93 3.4 MEA preparation and characterization for PEMWE 94 3.4.1 Membrane pretreatment 94 3.4.2 Catalysts inks composition 94 3.4.3 MEA preparation 95 3.4.4 Cell design and electrochemical characterization 96 3.5 Physico-chemical characterization of the DMFC materials 97 3.6 Electrochemical characterization of the DMFC materials 98 3.6.1 Experimental setup 98 3.6.2 Preparation of the DMFC electrodes 98 3.6.3 Electrochemical characterization of DMFC electrodes 99 3.7 MEA preparation and characterization for DMFC 100 3.7.1 MEA preparation 100 3.7.2 Cell design and electrochemical characterization 100 4. Results and discussion 103 4.1 PEM water electrolysis 103 4.1.1 Supports characterization 103 4.1.1.1 Formation of TiO2 nanotubes 103 4.1.1.2 Physico-chemical characterization of the supports 105 4.1.2 Hydrogen evolution electrocatalysts 114 4.1.2.1 Physico-chemical characterization 114 4.1.2.2 Electrochemical characterization 120 4.1.2.3. PtPd deposited on Nb-doped TNT 129 4.1.3 Oxygen evolution electrocatalysts 133 4.1.3.1 Physico-chemical characterization 134 4.1.3.2 Electrochemical characterization 138 4.1.4 Membrane electrode assemblies (MEAs) 152 4.1.4.1 Electrochemical characterization 153 4.1.4.2 Cost estimation 161 4.2 DMFC 171 4.2.1 Methanol oxidation reaction electrocatalyst 171 4.2.1.1 Physico-chemical characterization 171 4.2.1.2 Electrochemical characterization 175 4.2.2 Membrane electrode assemblies (MEAs) 181 5. Conclusions 189 6. References 193 APPENDIX 223 List of symbols 225 List of acronyms 227 Curriculum vitae 231 ELECTROCATALYST DEVELOPMENT FOR PEM WATER ELECTROLYSIS AND DMFC: TOWARDS THE METHANOL ECONOMY Abstract The concept of the so-called “methanol economy” suggests the use of methanol for: (i) energy storage means; (ii) readily transportation and fuel dispensing, especially for DMFC; (iii) feedstock for a wide variety of products and chemicals. The direct methanol fuel cell (DMFC) enables the direct conversion of the chemical energy stored in liquid methanol fuel to electrical energy, with water and carbon dioxide as by-products. They are very appropriate for portable applications. Compared to the more well-known hydrogen fueled polymer electrolyte membrane fuel cells (H2-PEMFCs), DMFCs present several advantages mainly related to the use of liquid fuel. Methanol, as a liquid, is significantly safer and easier to handle, transport and store. In addition, it is available at low cost, as well as its higher energy density than -1 H2 (6 kWh kg ). At present, methanol it is mostly prepared from synthesis gas (syn-gas, CO and H2 mixture), obtained mainly from the incomplete combustion of fossil fuels.
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