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

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