DOCSLIB.ORG

Polymeric Carbon Nitrides and Related Metal-Free Materials for Energy and Environmental Cite This: J

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Polymeric Carbon Nitrides and Related Metal-Free Materials for Energy and Environmental Cite This: J Journal of Materials Chemistry A View Article Online REVIEW View Journal | View Issue Polymeric carbon nitrides and related metal-free materials for energy and environmental Cite this: J. Mater. Chem. A, 2020, 8, 11075 applications Jesus´ Barrio, Michael Volokh and Menny Shalom * Carbon nitride polymers have emerged as a new class of materials for a wide range of applications such as photo- and electro-catalysis, sensors, bioimaging and more due to their chemical, photophysical and catalytic properties as well as their low-price, facile synthesis and high stability under harsh chemical conditions. In this review we begin with a broad overview of carbon-based materials, arriving at the focus of this review, polymeric carbon nitrides (CNs). After a brief overview of applications, we delve into their various synthetic methods, with an emphasis on achieving control on the nanoscale features of this intriguing polymeric semiconductor. The main synthetic pathways include co- polymerization at various stages, templating, an ionothermal pathway and harnessing of Received 19th February 2020 Creative Commons Attribution 3.0 Unported Licence. supramolecular pre-organization, which are discussedindetailalongwithCNgrowthanddeposition Accepted 1st April 2020 on substrates. Finally, we give our perspectives on the evolution of this field, the current limitations, DOI: 10.1039/d0ta01973a and elaboration of achievable control over the chemical composition, the electronic structure and rsc.li/materials-a the morphology of this family of materials. 1. Carbon materials: synthesis, applications and challenges This article is licensed under a Carbon materials ranging from graphene,1 carbon nanotubes (CNTs)2 or fullerenes3 to activated carbon and aerogels4 are Department of Chemistry and Ilse Katz Institute for Nanoscale Science and widely used for environmental and energy-related purposes5–8 Open Access Article. Published on 28 May 2020. Downloaded 9/26/2021 5:12:03 PM. Nanotechnology, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel. such as batteries,9,10 supercapacitors11 and electrocatalysis12,13 E-mail: [email protected] Jesus´ Barrio received his B.Sc in Michael Volokh received his BSc Chemistry from the Universidad in Chemistry and Chemical Autonoma´ de Madrid (Madrid, Engineering from the Ben-Gu- Spain) in 2014 and in 2016 rion University of the Negev his M.Sc in Nanoscience and (Israel). During his MSc and Molecular Nanotechnology PhD (2017), under the supervi- while working at the IMDEA sion of Prof. Taleb Mokari, he Nanoscience Institute. He then focused on gas- and liquid- carried out a research project at -phase synthesis and character- the Max Planck Institute for ization of inorganic hybrid Colloids and Interfaces where he nanostructures. His current developed a keen interest in the research interests include pho- design of carbon nitride mate- toelectrocatalysis, the formation rials and their application in photocatalysis. Aerwards, he moved of complex hybrid nano- along with his PhD supervisor, Prof. Menny Shalom, to the structures, and electrophoretic Chemistry Department of the Ben-Gurion University of the Negev deposition. where he is currently nishing his doctoral studies. His interests cover the design of low dimensional materials and hybrid struc- tures for energy-related applications. This journal is © The Royal Society of Chemistry 2020 J. Mater. Chem. A,2020,8, 11075–11116 | 11075 View Article Online Journal of Materials Chemistry A Review due to their conductivity, nanosized-derived effects (e.g.,dirac reactant molecules for various chemical reactions and there- points in graphene, metallic or semiconductor CNTs and fore their inclusion within C-materials has been a common electron accepting properties of fullerenes) and the possi- subject of research.33 bility of inducing defects by chemical design.14 There are Non-metallic elements have been typically included by numerous synthetic pathways to synthetize this class of a co-polymerization route from a C-source with heteroatom- materials, such as chemical vapor deposition (CVD),15–17 containing molecules at high temperatures or by direct pyrolysis of C-rich molecules,18–20 hydrothermal means, thermal calcination of (bio)molecules, such as amino acids etc.21–25 Nevertheless, in most catalysis and energy-related and ionic liquids.34–38 Wohlgemuth et al. obtained carbon scenarios, these materials serve as a support or as a plat- microspheres and aerogels co-doped with nitrogen and sulfur form for an additional active component or molecular by the hydrothermal treatment of glucose along with amino complex to perform a given reaction.26 The morphology and acids containing sulfur, and they studied their electro- properties of the nal carbon-based material strongly depend chemical performance for the oxygen reduction reaction on the synthetic pathway, as well as on the precursor.27 (ORR).39,40 Furthermore, S-doped C-materials were recently Additionally, utilizing foreign elements like templating explored for the nitrogen reduction reaction (NRR); Xia et al. agents or doping species28–30 can precisely tune the porous prepared S-doped carbon nanospheres by a hydrothermal structure and electronic conguration, towards their imple- reaction comprising glucose and benzyl disulde. The mentation in a wider range of applications.31,32 resulting materials showed excellent selectivity and a faradaic efficiency of 7.47% at À0.7 V versus (vs.)RHE,muchhigher than the undoped material (1.45%).41 Thepresenceof 2. Inserting heteroatoms into carbon heteroatoms within carbon materials strongly affects their matrices reactivity in elds such as electrocatalysis, batteries or supercapacitors. B and P, for example, display a lower elec- Creative Commons Attribution 3.0 Unported Licence. To modify the electronic structure of C-materials and enable tronegativity than carbon, which results in a charge redistri- semiconductor-like properties, such as UV/visible light bution and modies the adsorption modes of reactant absorption, the formation of defects through the insertion of molecules.42,43 The energy redistribution imprinted by heteroatoms has emerged as a promising approach. Chemical electron-decient heteroatoms in carbon materials has been elements that differ in parameters like the atomic radius or widely reported by various groups; boron-doped graphene, for electronegativity can induce effects on the materials that are example, showed enhanced NRR performance (10.8% faradaic benecial for their application in energy-related elds, i.e., efficiency at À0.5 V) due to the lower energy barrier for N2 44 the creation of a band gap or selectivity towards a given electroreduction within BC3 structures. Furthermore, the reaction. Furthermore, combining several heteroatoms in a C- presence of BC3 trimers within the hexagonal lattice of C This article is licensed under a matrix can produce synergistic effects such as the formation materials induces a p-type semiconductor behavior and the of reactive centers and a change in its intrinsic mechanical, resulting material displays unique sensing capabilities (e.g., 29 45 chemical, physical and electronic properties. The insertion to NO2 and NH3 toxic gases). Phosphorous incorporation by Open Access Article. Published on 28 May 2020. Downloaded 9/26/2021 5:12:03 PM. of nitrogen into a carbonaceous matrix is among the most pyrolysis or hydrothermal treatment also results in materials frequently reported methods, given the straightforward with catalytic sites, which are widely utilized as super- synthetic pathways for such an insertion; for example, capacitors and electrocatalysts.46–51 From the synthetic point a thermal treatment of precursors containing C–Nor of view, achieving homogeneity in the distribution of dopant a hydrothermal synthesis. Nevertheless, other heteroatoms, atoms within the lattice is a standing challenge; our group such as B, P, S, or metals, display a better affinity towards developed an approach to produce homogeneous heteroatom- doped carbons by utilizing polycyclicaromatichydrocarbons (PAHs) and heteroatom-containing species which melt during Prof. Menny Shalom received his a thermal reaction. During the polycondensation of PAHs with PhD from Bar Ilan University, Israel. For his postdoctoral research he joined the Max Planck Institute of Colloids and Interfaces (MPI), Germany, as a Minerva fellowship fellow. From 2013 to 2016 he was a group leader at the MPI and since the end of 2016 he has been an Associate Professor at the Ben-Gurion University of the Fig. 1 Synthetic procedure schemes for (a) C–N–B–O and (b) metal- Negev, Israel. His group is incorporated crystalline carbons using a molten-state synthesis. focused on the synthesis of new materials for photo-electrochemical Reproduced with permission from ref. 52 and 53, copyright (2018) cells and as electrocatalysts for water splitting. Wiley-VCH. 11076 | J. Mater. Chem. A,2020,8, 11075–11116 This journal is © The Royal Society of Chemistry 2020 View Article Online Review Journal of Materials Chemistry A heteroatom-containing molecules (or metal salts), their in 1986, Kouvetakis et al. have shown the preparation of BC3 sublimation is quenched, and the structural carbon is and C5N planar structures by thermal condensation of completely preserved thanks to the formation of new covalent a monomer containing B and N at high temperatures (800–1400 or coordination bonds. Using this method, boron, nitrogen, C).74 Mahmood et al. reported for the rst time the synthesis of oxygen, or different
Load more

Recommended publications
  • Facile Synthesis of Potassium Poly(Heptazine Imide) (PHIK)
    Subscriber access provided by CORNELL UNIVERSITY LIBRARY Article Facile synthesis of potassium poly(heptazine imide) (PHIK) / Ti-based Metal- Organic Framework (MIL-125-NH2) composites for photocatalytic applications Nicolás Artemio Rodríguez, Aleksandr Savateev, Maria Alejandra Grela, and Dariya Dontsova ACS Appl. Mater. Interfaces, Just Accepted Manuscript • Publication Date (Web): 13 Jun 2017 Downloaded from http://pubs.acs.org on June 14, 2017 Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
    [Show full text]
  • Solar Energy Harvesting with Carbon Nitrides: Do We Understand The
    Solar energy harvesting with carbon nitrides: Do we understand the mechanism? Wolfgang Domcke1, Johannes Ehrmaier1 and Andrzej L. Sobolewski2 1 Department of Chemistry, Technical University of Munich, D-85747 Garching, Germany 2 Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland Email: [email protected] (Wolfgang Domcke) Abstract The photocatalytic splitting of water into molecular hydrogen and molecular oxygen with sunlight is the dream reaction for solar energy conversion. Since decades, transition-metal- oxide semiconductors and supramolecular organometallic structures have been extensively explored as photocatalysts for solar water splitting. More recently, polymeric carbon nitride materials consisting of triazine or heptazine building blocks have attracted considerable attention as hydrogen-evolution photocatalysts. The mechanism of hydrogen evolution with polymeric carbon nitrides is discussed throughout the current literature in terms of the familiar concepts developed for photoelectrochemical water splitting with semiconductors since the 1970s. We discuss in this perspective an alternative mechanistic paradigm for photoinduced water splitting with carbon nitrides, which focusses on the specific features of the photochemistry of aromatic N-heterocycles in aqueous environments. It is shown that a water molecule which is hydrogen-bonded to an N-heterocycle can be decomposed into hydrogen and hydroxyl radicals by two simple sequential photochemical reactions. This concept is illustrated by first-principles calculations of excited-state reaction paths and their energy profiles for hydrogen-bonded complexes of pyridine, triazine and heptazine with a water molecule. It is shown that the excited-state hydrogen-transfer and hydrogen-detachment reactions are essentially barrierless, in sharp contrast to water oxidation in the electronic ground state, where high barriers prevail.
    [Show full text]
  • Photo-Induced Phenomena from the Quantum Chemist Point of View Tangui Le Bahers
    Photo-Induced Phenomena from the Quantum Chemist Point of View Tangui Le Bahers To cite this version: Tangui Le Bahers. Photo-Induced Phenomena from the Quantum Chemist Point of View. Theoretical and/or physical chemistry. Université Claude Bernard Lyon 1, 2018. tel-02073756 HAL Id: tel-02073756 https://hal.archives-ouvertes.fr/tel-02073756 Submitted on 22 Mar 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. MEMOIRE En vue de l’obtention du diplôme national de l’ Habilitation à diriger des recherches, délivré par l’Université Claude Bernard Lyon 1 Discipline : Chimie Laboratoire de Chimie de l’ENS Lyon Présenté publiquement le 14 Juin 2018 Par Monsieur Tangui LE BAHERS Photo-Induced Phenomena from the Quantum Chemist Point of View Devant le jury composé de : Dr. Valérie Keller CNRS / Université de Strasbourg Pr. Mario Barbatti Université d’Aix-Marseille Dr. Pascal Raybaud IFP Energies Nouvelles Dr. Filippo De Angelis CNR Perugia / Italy Pr. Christophe Morell Université Claude Bernard Lyon 1 Dr. Chantal Andraud CNRS / ENS Lyon Remerciements Voilà maintenant 7 ans que j’ai soutenu ma thèse. Ce manuscrit vient retracer les travaux scientifiques que j’ai réalisés depuis.
    [Show full text]
  • Graphitic Carbon Nitride (G-C3N4), an Organic Semiconductor That Proved a Suitable Photocatalyst for Hydrogen Production from Water
    METAL LOADED G-C₃N₄ FOR VISIBLE LIGHT-DRIVEN H₂ PRODUCTION Federica Fina A Thesis Submitted for the Degree of PhD at the University of St Andrews 2014 Full metadata for this item is available in St Andrews Research Repository at: http://research-repository.st-andrews.ac.uk/ Please use this identifier to cite or link to this item: http://hdl.handle.net/10023/6322 This item is protected by original copyright This item is licensed under a Creative Commons Licence Metal loaded g-C3N4 for visible light-driven H2 production by Federica Fina A thesis submitted in partial fulfilment for the degree of PhD at the University of St Andrews 2014 I, Federica Fina hereby certify that this thesis, which is approximately 50,000 words in length, has been written by me, and that it is the record of work carried out by me and that it has not been submitted in any previous application for a higher degree. I was admitted as a research student in January 2011 and as a candidate for the degree of Doctor of Philosophy in August 2014; the higher study for which this is a record was carried out in the University of St Andrews between 2011 and 2014. Date …………….………….. Signature of candidate …………….………….. I hereby certify that the candidate has fulfilled the conditions of the Resolution and Regulations appropriate for the degree of Doctor of Philosophy in the University of St Andrews and that the candidate is qualified to submit this thesis in application for that degree. Date …………….………….. Signature of supervisor …………….………….. In submitting this thesis to the University of St Andrews I understand that I am giving permission for it to be made available for use in accordance with the regulations of the University Library for the time being in force, subject to any copyright vested in the work not being affected thereby.
    [Show full text]
  • Efficient Removal of Antimony(III)
    water Article Efficient Removal of Antimony(III) in Aqueous Phase by Nano-Fe3O4 Modified High-Iron Red Mud: Study on Its Performance and Mechanism Yizhe Peng 1,2, Lin Luo 1,*, Shuang Luo 1, Kejian Peng 2, Yaoyu Zhou 1, Qiming Mao 1, Jian Yang 1 and Yuan Yang 1,* 1 International Joint Laboratory of Hunan Agricultural Typical Pollution Restoration and Water Resources Safety Utilization, College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China; [email protected] (Y.P.); [email protected] (S.L.); [email protected] (Y.Z.); [email protected] (Q.M.); [email protected] (J.Y.) 2 Hunan Key Laboratory of Water Pollution Control Technology, Hunan Research Academy of Environmental Sciences, Changsha 410004, China; [email protected] * Correspondence: [email protected] (L.L.); [email protected] (Y.Y.); Tel.: +86-0731-8463-8343 (L.L.) Abstract: The resource utilization of excess red mud produced from aluminum production is a current research focus. In this study, novel nano-Fe3O4 modified high-iron red mud material (HRM@nFe3O4) was fabricated using the method of co-precipitation to remove Sb(III) from the aqueous phase. The HRM@nFe3O4 at a nFe3O4:HRM mass ratio of 1:1 had optimal adsorbing performance on Sb(III) in water. Compared with others, the synthetic HRM@nFe3O4 sorbent had a superior maximum Sb(III) adsorption capacity of 98.03 mg·g−1, as calculated by the Langmuir model, and a higher 2 −1 specific surface area of 171.63 m ·g , measured using the Brunauer-Emmett-Teller measurement. The adsorption process was stable at an ambient pH range, and negligibly limited by temperature Citation: Peng, Y.; Luo, L.; Luo, S.; the coexisting anions, except for silicate and phosphate, suggesting the high selectivity toward Sb(III).
    [Show full text]
  • Heptazine Imide Salts Can Exchange Metal Cations in the Solid State
    MPIKG Public Access Author Manuscript Published in final edited form as: Savateev, A., Pronkin, S., Willinger, M. G., Antonietti, M., & Dontsova, D. (2017). Towards Organic Zeolites and Inclusion Catalysts: Heptazine Imide Salts Can Exchange Metal Cations in the Solid State. Chemistry – An Asian Journal, 12(13), 1517-1522. doi:10.1002/asia.201700209. Towards organic zeolites and inclusion catalysts: heptazine imide salts can exchange metal cations in the solid state Savateev, A., Pronkin, S., Willinger, M. G., Antonietti, M., & Dontsova, D. Worth its salt: A variety of heptazine imide salts and a free base can be easily prepared by a simple ion exchange starting from the synthesized potassium derivative. Thus, various mono- and bivalent cations can be incorporated in the structure that resembles the behavior of zeolites. The photocatalytic activity in visible-light-driven hydrogen evolution is shown to depend on the nature of the introduced cation and reaches its maximum in the case of the Mg-salt. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Towards organic zeolites and inclusion catalysts: heptazine ipt imide salts can exchange metal cations in the solid state Aleksandr Savateev1, Sergey Pronkin2, Marc Willinger1,3, Markus Antonietti1, and Dariya Manuscr 1* Dontsova Abstract. Highly crystalline potassium (heptazine imides) were preparations. In addition, intercalation of chloride and prepared by the thermal condensation of substituted 1,2,4- · Author · bromide changes the gallery heights of the graphitic triazoles in eutectic salt melts. These semiconducting salts are already known to be highly active photocatalysts, e.g.
    [Show full text]
  • From Triazines to Heptazines: Novel Nonmetal Tricyanomelaminates As Precursors for Graphitic Carbon Nitride Materials
    Chem. Mater. 2006, 18, 1891-1900 1891 From Triazines to Heptazines: Novel Nonmetal Tricyanomelaminates as Precursors for Graphitic Carbon Nitride Materials Bettina V. Lotsch and Wolfgang Schnick* Department Chemie und Biochemie, Lehrstuhl fu¨r Anorganische Festko¨rperchemie, Ludwig-Maximilians-UniVersita¨t Mu¨nchen, Butenandtstrasse 5-13, D-81377 Mu¨nchen, Germany ReceiVed October 25, 2005. ReVised Manuscript ReceiVed December 22, 2005 The first non-metal tricyanomelaminates have been synthesized via metathesis reactions and characterized by means of single-crystal X-ray diffraction and vibrational and solid-state NMR spectroscopy. The crystal structures of [NH4]2[C6N9H] (1)(P21/c, a ) 1060.8(2) pm, b ) 1146.2(2) pm, c ) 913.32(18) pm, â ) 6 3 112.36(3)°, V ) 1027.0(4) × 10 pm ), [C(NH2)3]3[C6N9]‚2H2O(2)(P212121, a ) 762.12(15) pm, b ) 6 3 1333.6(3) pm, c ) 1856.6(4) pm, V ) 1887.0(7) × 10 pm ) and [C3N6H7]2[C6N9H]‚2.5 H2O(3)(P1h, a ) 1029.5(2) pm, b ) 1120.3(2) pm, c ) 1120.7(2) pm, R)104.22(3)°, â ) 112.74(3)°, γ ) 104.62- (3)°, V ) 1064.8(4) × 106 pm3) are composed of singly protonated (1 and 3) or nonprotonated (2) tricyanomelaminate ions, which, together with the respective counterions, form two-dimensional, layered structures (1 and 3) or a quasi three-dimensional network (2). Particular emphasis has been placed on the elucidation of the thermal reactivity of the three molecular salts by means of thermal analysis and vibrational and NMR spectroscopy, as well as temperature-dependent X-ray powder diffraction.
    [Show full text]
  • 2,5,8-Trihydrazino-S-Heptazine
    2,5,8-Trihydrazino-s-heptazine: a precursor for heptazine-based iminophosphoranes Edwin Kroke, Tatyana Saplinova, Vadym Bakumov, Tobias Gmeiner, Jörg Wagler, Marcus Schwarz To cite this version: Edwin Kroke, Tatyana Saplinova, Vadym Bakumov, Tobias Gmeiner, Jörg Wagler, et al.. 2,5,8- Trihydrazino-s-heptazine: a precursor for heptazine-based iminophosphoranes. Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, Wiley-VCH Verlag, 2009, 10.1002/zaac.200900311. hal-00518304 HAL Id: hal-00518304 https://hal.archives-ouvertes.fr/hal-00518304 Submitted on 17 Sep 2010 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. ZAAC 2,5,8-Trihydrazino-s-heptazine: a precursor for heptazine- based iminophosphoranes Journal: Zeitschrift für Anorganische und Allgemeine Chemie Manuscript ID: zaac.200900311.R1 Wiley - Manuscript type: Article Date Submitted by the 17-Jul-2009 Author: Complete List of Authors: Kroke, Edwin; TU Bergakademie Freiberg, Institut fuer Anorganische Chemie Saplinova, Tatyana; TU Bergakademie Freiberg,
    [Show full text]
  • Investigations Into S-Heptazine-Based Carbon Nitride Precursors
    Dissertation zur Erlangung des Doktorgrades der Fakultät für Chemie und Pharmazie der Ludwig-Maximilians-Universität München Investigations into s-Heptazine-Based Carbon Nitride Precursors Andreas Sattler aus Augsburg 2010 Erklärung Diese Dissertation wurde im Sinne von § 13 Abs. 3 bzw. 4 der Promotionsordnung vom 29. Januar 1998 von Herrn Prof. Dr. Wolfgang Schnick betreut. Ehrenwörtliche Versicherung Diese Dissertation wurde selbstständig, ohne unerlaubte Hilfe erarbeitet. München, den 12.02.2010 Andreas Sattler Dissertation eingereicht am 15.02.2010 1. Gutachter: Prof. Dr. Wolfgang Schnick 2. Gutachter: Prof. Dr. Dirk Johrendt Mündliche Prüfung am 20. April 2010 ii Für meine Familie und Freunde Und für alle denen dies Information und Hilfe sein mag iii iv Acknowledgements First of all, I would like to express my gratitude to Prof. Dr. Wolfgang Schnick for hav- ing granted me the opportunity to work in his research group. His guidance and expertise have been invaluable for the present work. I am most grateful to Prof. Dr. Dirk Johrendt for his willingness to be the co-referee of this thesis. I thank Prof. Dr. Bettina V. Lotsch, Prof. Dr. Jürgen Senker, Prof. Dr. Konstantin Karaghiosoff and Priv. Doz. Dr. Klaus Müller-Buschbaum for being available as examiners in my viva-voce. The past and present members of the work group and other members of the department, whose company I have had the honor to enjoy, have helped and supported me in a multitude of ways. Working with these fine colleagues has become a part of my life that I will look back upon often and happily. I would like to address special thanks and gratitude to: My predecessors Dr.
    [Show full text]
  • Structure Elucidation of Polyheptazine Imide by Electron Diffraction
    View Article Online / Journal Homepage / Table of Contents for this issue COMMUNICATION www.rsc.org/chemcomm | ChemComm Structure elucidation of polyheptazine imide by electron diffraction—a templated 2D carbon nitride networkw Markus Do¨blinger,a Bettina V. Lotsch,a Julia Wack,b Ju¨rgen Thun,b Ju¨rgen Senkerb and Wolfgang Schnick*a Received (in Cambridge, UK) 10th November 2008, Accepted 9th January 2009 First published as an Advance Article on the web 27th January 2009 DOI: 10.1039/b820032g Structure elucidation of a condensed carbon(IV) nitride with a owing to the lack of single-crystal data. Electron diffraction is stoichiometry close to C3N4 by electron diffraction reveals a a powerful tool to deliver on both requirements by locally two-dimensional planar heptazine-based network containing probing the real structure of nanocrystalline materials and isolated melamine molecules in the trigonal voids. minority phases not previously accessible to bulk structural analysis. Owing to their exceptional chemical stability and hardness, Here, we communicate the structure elucidation of a crys- nitrides of main group elements have entered the stage as talline 2D carbon nitride network with the formula ubiquitous light-weight, high-performance materials relevant to (C6N7)2(NH)3ÁC3N3(NH2)3 by electron diffraction. This novel a multitude of technological applications. Although 3D phases of member of the carbon nitride family, featuring an intermediate binary carbon nitride C3N4 hold promise as new ultra-hard condensation stage halfway between melon and g-C3N4, may materials,1 the layered polymorph, graphitic carbon nitride shed light on structural implications and stability considerations (g-C3N4) has recently garnered attention for its versatile optical, associated with graphitic carbon nitride.
    [Show full text]
  • © Copyright 2020 Emily Rabe
    © Copyright 2020 Emily Rabe The Role of Excited-State Energy Landscapes in Directing Electron and Proton Motion for Light Harvesting Applications Emily Rabe A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Washington 2020 Reading Committee: Cody Schlenker, Chair Brandi Cossairt Munira Khalil Program Authorized to Offer Degree: Chemistry University of Washington Abstract The Role of Excited-State Energy Landscapes in Directing Electron and Proton Motion for Light Harvesting Applications Emily Rabe Chair of the Supervisory Committee: Professor Cody Schlenker Department of Chemistry To meet the increasing global demand for energy we need to innovate new ways to harness and convert renewable energy sources. Solar energy provides a huge potential to meet these demands, but there is still a plethora of unanswered questions surrounding how photons interact with organic molecules and materials, particularly in the field of photovoltaics and photochemistry. The low dielectric constant of these organic materials causes them to behave differently than their inorganic counterparts. Chapter 2 provides background for the variety of applications of organic optoelectronic materials and common techniques used to study them. In recent years, the aza-aromatic material carbon nitride, and its monomer unit, heptazine, has seen a surge in popularity to mediate photochemical transformations, particularly hydrogen evolution. Yet despite the thousands of publications in this field, there are few fundamental photophysical studies, which are critical to enable new reaction pathways. This work describes a series of photophysical explorations into a molecular heptazine derivative, 2,5,8-tris(4- methoxyphenyl)-1,3,4,6,7,9,9b-heptaazaphenalene (TAHz).
    [Show full text]
  • Chemistry of Layered D-Metal Pnictide Oxides and Their Potential As Candidates for New Superconductors
    Published in Sci. Technol. Adv. Mater. 9 (2008) 033003 on October 8th, 2008 Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors Tadashi C. Ozawa*† and Susan M. Kauzlarich‡ †Nanoscale Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan ‡Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, U.S.A. * To whom correspondence should be addressed. E-mail: [email protected]. Phone: +81-29-860-4722. FAX: +81-29-854-9061. Abstract Layered d-metal pnictide oxides are a unique class of compounds which consist of characteristic d-metal pnictide layers and metal oxide layers. More than 100 of these layered compounds, including the recently discovered Fe-based superconducting pnictide oxides, can be classified into nine structure types. These structure types and the chemical and physical properties of the characteristic d-metal pnictide layers and metal oxide layers of the layered d-metal pnictide oxides are reviewed and discussed. Furthermore, possible approaches to design new superconductors based on these layered d-metal pnictide oxides are proposed. Keywords: low-dimensional compound, structure-property relationship, suboxide, CDW (charge-density wave), SDW (spin-density wave) 1. Introduction The recent discovery of superconductivity in the Fe-based layered pnictide oxide has sparked immense interest in the chemistry and physics communities reminiscent of the discovery of the high-Tc cuprate superconductors in the mid-1980’s [1-3]. Pnictide oxides, which are also called “oxypnictides,” are a unique class of compounds. Group 15 elements (N is often excluded) are called “pnictogens” or “pnicogens,” and their anionic forms or compounds containing anionic pnictogens are called “pnictides” [4].
    [Show full text]