Engineering the Interfacial Microenvironment via Surface Hydroxylation to Realize the Global Optimization of Electrochemical CO 2 Reduction.

The adsorption and activation of CO 2 on the electrode interface is a prerequisite and key step for electrocatalytic CO 2 reduction reaction (eCO 2 RR). Regulating the interfacial microenvironment to promote the adsorption and activation of CO 2 is thus of great significance to optimize overall conversion efficiency. Herein, a CO 2 -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 CO 2 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 CO 2 -philic groups is a promising way to achieve the global optimization of eCO 2 RR via promoting adsorption and activation of CO 2 .