Engineering the Interfacial Microenvironment via Surface Hydroxylation to Realize the Global Optimization of Electrochemical CO₂ Reduction

The adsorption and activation of CO2 on the electrode interface is a prerequisite and key step for electrocatalytic CO2 reduction reaction (eCO2 RR). Regulating the interfacial microenvironment to promote the adsorption and activation of CO2 is thus of great significance to optimize overall conversion efficiency. Herein, a CO2-philic hydroxyl coordinated ZnO (ZnO-OH) catalyst is fabricated, for the first time, via a facile MOF-assisted method. In comparison to the commercial ZnO, the as-prepared ZnO-OH exhibits much higher selectivity toward CO at lower applied potential, reaching a Faradaic efficiency of 85% at -0.95 V versus RHE. To the best of our knowledge, such selectivity is one of the best records in ZnO-based catalysts reported till date. Density functional theory calculations reveal that the coordinated surficial -OH groups are not only favorable to interact with CO2 molecules but also function in synergy to decrease the energy barrier of the rate-determining step and maintain a higher charge density of potential active sites as well as inhibit undesired hydrogen evolution reaction. Our results indicate that engineering the interfacial microenvironment through the introduction of CO2-philic groups is a promising way to achieve the global optimization of eCO2 RR via promoting adsorption and activation of CO2.