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 rationalise non-covalent interactions between electrolyte and surface adsorbates in electrocatalysis. Three main schools of thought have rationalised the effect of the electrolyte-adsorbates-surface interactions on the reaction kinetics, each based on different descriptors. The first suggests that non-covalent interactions with the electrolyte modify the binding energies of adsorbed intermediates. The second highlights the role of charge and electric fields near the electric double layer, shaped by the potential of zero charge, in stabilising polar adsorbates and governing proton transfer. The third focuses on energy barriers arising from the restructuring of the water solvation spheres of both electrolyte and reactants. We critically examine the main arguments and limitations of each framework, with a focus on hydrogen evolution and carbon dioxide reduction, and outline experimental challenges and future directions for elucidating electrolyte effects in electrocatalysis.