Effects of Electrolyte Ionic Species on Electrocatalytic Reactions: Advances, Challenges, and Perspectives

Abstract Electrolytes have a profound impact on the chemical environment of electrocatalysis, influencing the reaction rate and selectivity of products. Experimental and theoretical studies have extensively investigated the interaction mechanisms between electrolyte ions (i.e., alkali metal cations, carbonate anions) and reactants or the catalyst surface in electrocatalytic reactions such as the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, water oxidation reaction, and CO 2 reduction reaction. Past studies have demonstrated a noticeable dependence of electrochemical reaction activity and selectivity on the identity of electrolyte ions. However, few overviews have comprehensively and specifically discussed the effects of electrolyte cations and anions on common electrochemical reactions. In order to clarify and give more insights on this research area, this review aims to summarize and highlight recent progress in understanding the effects of various electrolyte ionic species and their influence mechanisms in diverse electrocatalytic reactions for water splitting, H 2 O 2 production, and CO 2 reduction. The challenges and perspectives on the effect of electrolyte ions in electrocatalysis are also presented.