Electrolyte effects in proton-electron transfer reactions and implications for renewable fuels and chemicals synthesis

Electrolyte effects play a fundamental role in electrocatalysis, influencing reaction kinetics, selectivity, and catalyst stability by altering interfacial interactions and charge distribution. This perspective reports recent advances to rationalize non-covalent interactions between electrolyte and surface adsorbates in modulating the reaction kinetics in electrocatalysis. Three main schools of thought have rationalized the effect of the electrolyte-adsorbates-surface interactions on the reaction kinetics, each of them based on different descriptors: i) The interactions with the electrolyte modify the binding energies of adsorbed reaction intermediates, which determine the energetic barriers and kinetics of a reaction. ii) The charge and electric field near the electric double layer, affected by the potential of zero charge of the catalyst surface, stabilize the energetics of the polar adsorbates and control the proton transfer kinetics. iii) Energy barriers arising from the restructuring of the water solvation spheres of both electrolyte and reactants affect the kinetics of the reaction. Herein, we will examine the main arguments and limitations of these three schools of thought, with a special focus on the hydrogen evolution and carbon dioxide electroreduction reactions to carbon monoxide and fuels and chemicals. Finally, we will analyze which ˈexperimental challengesˈ need to be overcome to accurately describe the electric double layer structure and electrolyte role in electrocatalysis.