Wettability control in electrocatalytic CO₂ reduction: Effects, modulations and mechanisms

Wettability control at the electrolyte/electrode interface represents a critical factor governing the fundamental mechanisms of reaction pathways and kinetics in practical electrocatalysis. Under an applied electrical field, a variety of physicochemical events take place at the electrolyte/electrode interface consisting of gas diffusion layers (GDL) and electrical double layers (EDL), including the transportation of kinetically relevant species, the dynamic desorption/adsorption of surface species and surface reactions. Here, using CO₂ electrocatalytic reduction (CO₂ER) as a model system, we review the fundamentals of wettability, existing and emerging means for the modulation and characterization of wettability, a molecular-level understanding of the effect of wettability at the electrolyte/electrode interface, followed by critically reviewing existing issues and future prospects of wettability control in general electrocatalysis. The review aims to systematically construct a physicochemical model of the liquid/solid interface under the influence of wettability, examining its effect on CO₂ER and general electrocatalytic systems, thereby providing insights for subsequent electrocatalytic reactions.