Confined cavity on a mass-producible wrinkle film promotes selective CO 2 reduction

Reduction of CO 2 to carbon monoxide (CO) is the starting point for producing valuable carbon chemicals and liquid fuels. To date, efficient CO 2 electroreduction to CO has been accomplished predominantly by using the control of the structural parameters of a catalyst, including its nanostructure and surface morphology. In this study, the highly selective CO formation (∼90% of faradaic efficiency) at a low applied potential (−0.4 V vs. reverse hydrogen electrode) is reported by using the control of the local pH near the reaction site, which has been of less interest compared to other factors in prior studies. The local pH near the reaction site was controlled by using a confined cavity in the Au wrinkle film. Experimental and computational calculation results revealed that such enhancement is mainly related to the few-micrometer-amplitude confined space in the tens of nanometers thickness Au wrinkle film. Notably, the fabrication of the wrinkle catalyst film was extremely simple, permitting large-scale fabrication.