Engineering a Cu/ZnO<i><sub>x</sub></i> Interface for High Methane Selectivity in CO<sub>2</sub> Electrochemical Reduction
Ruize Wang, Ran Jiang, Cunku Dong, Tianbai Tong, Zhe Li, Hui Liu, Xi‐Wen Du
Abstract
An oxidized copper species (Cuδ+) on the metallic copper surface is critical to the activity and selectivity of electrochemical reduction of CO2 gas. However, Cuδ+ species are easily reduced under working conditions of CO2 electroreduction. Herein, we propose an interface engineering strategy to stabilize Cuδ+ species; specifically, ZnOx nanoparticles are grown on a copper foil to generate a Cu/ZnOx interface. The interface stabilizes the surface Cu2+ species and delivers high methane selectivity (∼36%) and long-term durability (>12 h) at a potential of −1.1 V versus reversible hydrogen electrode (RHE) for CO2 reduction. By combining comprehensive characterizations with simulation experiments, we identify cupric species as active sites for CH4 formation, which is confirmed by density functional theory calculations. Our work demonstrates that interface engineering is a promising way to stabilize active sites and boost selective CO2 electroreduction.