Operando spectroscopic methods to study electrochemical processes Proefschrift ter verkrijging van de graad van doctor aan de Technische Universiteit Delft, op gezag van de Rector Magnificus Prof.dr.ir. T.H.J.J. van der Hagen, voorzitter van het College voor Promoties, in het openbaar te verdedigen op vrijdag 5 juni 2020 om 12:30 uur door Nienke Joan FIRET Master of Science in Chemical Engineering Master of Science in Sustainable Energy Technology Universiteit Twente, Nederland This dissertation has been approved by the promotors. Composition of the doctoral committee: Rector Magnificus chairman Dr. W.A. Smith Delft University of Technology, promotor Prof.dr. B. Dam Delft University of Technology, promotor Independent members: Prof.dr. A. Urakawa Delft University of Technology Prof.dr. M. Tromp University of Groningen Prof.dr.ir. J. Huskens University of Twente Dr. M. Escudero Escribano University of Copenhagen, Denmark Prof.dr. H. Geerlings Delft University of Technology, reserve member Other member: Dr. A. Longo European Synchrotron Radiation Facility, France This work is part of the ‘APPEL’ project, funded by the Netherlands Organisation for Scientific Research (NWO) and Shell. Synchrotron experiments were funded by grants acquired from DUBBLE (part of NWO) and the European Synchrotron Radiation Facility (ESRF). Front cover artwork by: Studio Hudson, Amsterdam. studiohudson.nl Printed by: GVO drukkers & vormgevers B.V. Copyright © 2020 by N.J. Firet ISBN 978-94-6384-137-5 An electronic version of this dissertation is available at repository.tudelft.nl Or perhaps – but here I speculate, here my own curiosity leads me by the nose – the world is so arranged that when all things are learnt, when curiosity is exhausted (so, long live curiosity), that is when the world shall have come to its end. By Graham Swift, in Waterland (1983) I have been to the year 3000. Not much has changed but they lived under water. And your great great great granddaughter. Is pretty fine. By Busted, The Year 3000 (2002) Table of contents 1 Introduction and Theory................................................................................................... 7 Introduction ................................................................................................................. 8 Theory........................................................................................................................... 2 Aim of this thesis and research questions ............................................................. 26 References .................................................................................................................. 28 2 Probing the reaction mechanism of CO2 electroreduction over Ag films via operando infrared spectroscopy ........................................................................................... 32 Foreword .................................................................................................................... 33 Abstract ...................................................................................................................... 33 Introduction ............................................................................................................... 34 Results and discussion ............................................................................................. 37 Conclusions................................................................................................................ 45 Experimental section ................................................................................................ 45 References .................................................................................................................. 48 Appendix A ......................................................................................................................... 51 3 Operando EXAFS study reveals presence of oxygen in oxide-derived silver catalysts for electrochemical CO2 reduction ...................................................................... 59 Introduction ............................................................................................................... 61 Results and discussion ............................................................................................. 63 Conclusions................................................................................................................ 78 References .................................................................................................................. 79 Appendix B .......................................................................................................................... 83 4 Copper and silver gas diffusion electrodes performing CO2 reduction studied through operando X-ray absorption spectroscopy ............................................................ 93 Introduction ............................................................................................................... 95 Results – Guide to operando XAS on a GDE......................................................... 97 Results – operando XAS on copper GDEs ........................................................... 103 Results – operando XAS on silver GDEs ............................................................. 109 Discussion ................................................................................................................ 112 Conclusions ..............................................................................................................114 Experimental section ...............................................................................................114 References .................................................................................................................117 Appendix C ........................................................................................................................123 5 Chemisorption of anionic species from the electrolyte alters the surface electronic structure and composition of photocharged BiVO4 ..........................................................126 Introduction ..............................................................................................................128 Experimental section ...............................................................................................130 Results .......................................................................................................................132 Discussion .................................................................................................................142 Conclusions ..............................................................................................................144 References ...........................................................................................................................146 Appendix D ........................................................................................................................151 6 Outlook ............................................................................................................................160 The role of science versus industry .......................................................................160 Techno-economic background ...............................................................................161 Conclusion ................................................................................................................163 References .................................................................................................................164 Summary.................................................................................................................................165 Samenvatting..........................................................................................................................168 List of publications ................................................................................................................171 Acknowledgements ...............................................................................................................172 Curriculum Vitae ...................................................................................................................174 1 Introduction and Theory Introduction and Theory Introduction 30 years from now it will be 2050. According to the European and Dutch policy plans, the Netherlands should emit 80 to 100% less greenhouse gasses compared to 1990 by then. What does this mean? What does that world look like? You may now envision lush green landscapes filled with wind turbines and solar panels on every roof, something like the picture depicted in Figure 1.1a. In this image that is printed in your mind by graphic designers, you see a happy green economy. But when you do the math, you will soon realise that realistically, wind turbines and solar panels alone will not nearly be able to cover our energy demand. One of the main reasons for this is the type of energy these resources produce: electricity. In the world’s energy mixture, electricity is only 30% of what we use. The rest of our energy usage is accounted for by fuels and materials. Fuels are needed for transport, and materials are often produced in highly energy intensive processes such as the extraction of metals from their ores or fertilizer production. Therefore we need new technologies to create renewable fuels and materials. How will we provide >733 EJ (30%