Promoting CO2 Electroreduction Kinetics on Atomically Dispersed Monovalent Zn(I) Sites by Rationally Engineering Proton-feeding Centers.

Electrocatalytic reduction of CO2 (CO2RR) to value-added chemicals is of great significance for CO2 utilization. Due to the slow proton-feeding rates from sluggish water dissociation kinetics, however, the CO2RR process involving multi-electron and proton transfer is greatly limited by poor selectivity and low yield. Herein, we develop an atomically dispersed monovalent zinc anchored on nitrogenated carbon nanosheets (Zn/NC NSs) as an efficient catalyst for CO2RR. Benefiting from the unique coordination environment and atomic dispersion, the optimized Zn/NC NSs exhibits a superior CO2RR performance, featured by a high current density up to 50 mA cm-2 with an outstanding CO Faradaic efficiency of ～95%. The center Zn(I) atom coordinated with three N atoms and one N atom that bridge over two adjacent graphitic edge (Zn-N3+1) is identified as the catalytically active site by thorough structural characterizations. In-situ attenuated total reflectance infrared absorption spectroscopy results reveal that the twisted Zn-N3+1 structure accelerates the CO2 activation and protonation in the rate-determining step of *CO2 to *COOH on the rationally engineered proton-feeding centers, while theoretical calculations elucidate that atomically dispersed Zn-N3+1 moieties decrease the potential barriers for the intermediate COOH* formation, promoting the proton-coupled CO2RR kinetics and boosting the overall catalytic performance. A rechargeable Zn-CO2 battery based on the Zn/NC NS cathode delivers a maximal power density of 1.8 mW cm-2.