Multiple proton-coupled electron transfer for electrochemical generation of fuels.
This talk will outline a simple but general theoretical analysis for multiple proton-electron transfer reactions, based on the microscopic theory of proton-coupled electron transfer reactions, recent developments in the thermodynamic theory of multi-step electron transfer reactions, and the experimental realization that many multiple proton-coupled electron transfer reactions feature decoupled proton-electron steps in their mechanism. It is shown that decoupling of proton and electron transfer leads to a strong pH dependence of the overall catalytic reaction, implying an optimal pH for high catalytic turnover, and an associated optimal catalyst at the optimal pH. When more than one catalytic intermediate is involved, scaling relationships between intermediates may dictate the optimal catalyst and limit the extent of reversibility that may be achievable for a multiple proton-electron-transfer reaction. These scaling relationships follow from a valence-bond-type binding of intermediates to the catalyst surface. The theory is discussed in relation to the experimental results for a number of redox reactions that are of importance for sustainable energy conversion, including the electrocatalytic reduction of CO2, focusing on their pH dependence and structure sensitivity.
Marc Koper is Professor of Surface Chemistry and Catalysis at Leiden University, The Netherlands. He received his PhD degree (1994) from Utrecht University (The Netherlands) with Prof. J.H.Sluyters on a thesis on nonlinear dynamics and oscillations in electrochemistry. He was an EU Marie Curie postdoctoral fellow at the University of Ulm (Germany) and a Fellow of Royal Netherlands Academy of Arts and Sciences (KNAW) at Eindhoven University of Technology, before moving to Leiden University in 2005. He was awarded with the Hellmuth Fischer Medal of the German Society for Chemical Technology (DECHEMA) in 2012, with the Carl Wagner Memorial Award of the Electrochemical Society in 2013, with the Brian Conway Prize for Physical Electrochemistry of the International Society of Electrochemistry in 2016, and with Faraday Medal of the Royal Society of Chemistry in 2017. He is member of the Royal Netherlands Academy of Arts and Sciences (KNAW) since 2017. His main research interests are in fundamental aspects of electrocatalysis, theoretical electrochemistry, and electrochemical surface science.
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