Electrolyte effects on reaction kinetics in electrochemical CO2 reduction: The roles of pH, cations, and anions

The electrochemical reduction of CO2 (CO2 RR) holds significant potential for converting CO2 into value-added fuels and chemicals under mild reaction conditions. The kinetics of CO2 RR is strongly influenced by both the electrocatalysts and the local environment at the electrode/electrolyte interface. While considerable research has focused on elucidating the "structure-activity" relationships of electrocatalysts, a fundamental understanding of the role of electrolyte-related factors (such as the ionic species) near the electrode/electrolyte interface is highly important for the further enhancement in the catalytic performance of CO2 RR. In this review, we discuss the effects of pH, cations, and anions in the vicinity of the catalyst, using CO2 RR as a model reaction. The mechanistic understanding of these effects is also analyzed via experimental findings from in situ spectroscopic techniques and theoretical insights from density functional theory simulations. This review underscores the importance of understanding the various interactions of electrolytes with catalyst surfaces or intermediates and their impact on reaction kinetics of CO2 RR.