The role of interfacial water in promoting C–C coupling during CO2 electroreduction

The electrochemical reduction of CO₂ (CO₂RR) into hydrocarbons and oxygenates presents a promising pathway toward a carbon-neutral energy cycle, but achieving selective product formation remains a challenge. While extensive efforts have focused on catalyst design and electrolyte composition, the role of the interfacial water properties, an often-overlooked parameter, has only recently come under investigation. Water serves as the primary proton donor (in aqueous electrolytes) in the absence of hydronium, which can influence the competition between CO₂RR and the hydrogen evolution reaction (HER). Despite studies dating back to the 1980s demonstrating that electrolyte composition significantly impacts CO₂RR performance, the effects of the electrolyte composition on the interfacial water properties have remained largely unexplored. Recent findings suggest that tuning the interfacial water properties can influence C–C coupling by altering solvation environments and stabilize reaction intermediates. This perspective explores how tuning the interfacial water properties improves C–C coupling, providing a new strategy for improving catalysis.