Understanding the role of the electrolyte composition in electrocatalysis: How electrolytes control the catalytic activity

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Recently leading groups worldwide have empirically identified a number of systems where certain electrolyte compositions unexpectedly increase the overall activity of electrocatalytic materials. However, there is a severe lack of fundamental understanding of why typically inert species, like Li+, Na+, or K+, can increase the activity. The "positive" electrolyte effect is often even more pronounced than that obtained by optimizing the surface electronic structure and electrode composition. Unfortunately, the current understanding in the field is still not at the level to steadily predict the activity trends in this case. In this proposal, the focus is set on the systematic investigation of such electrolyte effects. The central hypothesis to elaborate on is that for a given electrode structure and composition, the so-called potential of maximum entropy of the formation of the electric double layer is primarily responsible for the observed electrolyte influence. It is important to note that the potential of maximum entropy should be distinguished from the potential of zero charge. There could be several potential maximum entropy or none within the stability region of electrodes, as was shown recently. This opens up a new degree of freedom to explore ways of increasing the performance of electrocatalytic systems. Modern techniques, including classical electrochemical and Raman methods and the unique laser-induced current transient spectroscopy, will be used to elaborate an approach capable of explaining and predicting the above-mentioned electrolyte effects. Reactions relevant to the generation and use of renewable hydrogen fuel (hydrogen evolution, oxygen evolution, and oxygen reduction reactions) will be used as the model processes. Metal oxide/hydroxide electrocatalysts derived metal-organic frameworks (MOFs), in particular, derived from surface-mounted MOFs (i.e., SURMOFs), as well as single crystal metal, metal-alloy electrodes, will be used as the model surfaces in this study to elaborate highly efficient electrocatalytic systems and understand the role of the electrolyte composition in the increased activity.