Engineering Interfacial Water for Advanced Electrocatalytic CO₂ Reduction: From Molecular Understanding to Materials Design.

Abstract

Electrocatalytic CO₂ reduction (CO₂RR) offers a direct pathway for converting CO₂ gas into fuels and value-added chemicals. However, achieving CO₂RR with high activity and stability remains a significant challenge. While previous research has predominantly focused on catalyst design, the role of interfacial water has often been overlooked. Interfacial water can act as the primary proton donor, directly influencing the competition between CO₂RR and the hydrogen evolution reaction. Moreover, the dynamic hydrogen-bond network of interfacial water can significantly alter the water dissociation barrier, thereby enhancing selectivity toward CO₂RR products. This review systematically summarizes the fundamental properties of interfacial water in CO₂RR, classifies the strategies for modulating interfacial water, and discusses the applicability of these strategies and their impact on CO₂RR performance. Particular emphasis is placed on the effect of interfacial water structural evolution on the CO₂RR mechanism, as well as the corresponding characterization techniques. This review provides a structured framework for the study of interfacial water in CO₂RR and offers guidance for the rational design of high-efficiency catalysts.