Insight into the Electrochemical CO2-to-Ethanol Conversion Catalyzed by Cu2S Nanocrystal-Decorated Cu Nanosheets

Ethanol (C2H5OH) is an economically ideal C2 product in electrochemical CO2 reduction. However, the CO2-to-C2H5OH conversion yield has been rather low and the underlying catalytic mechanism remains vague or unexplored in most cases. Herein, by decorating small Cu2S nanocrystals uniform ly on Cu nanosheets, three desirable features are integrated into the electrocatalyst, including a relatively high positive local charge on Cu (Cuδ+), abundant interfaces between Cuδ+ and zero-valence Cu0, and a non-flat, stepped catalyst surface, leading to the promoted affinity of *CO, decreased *COCO formation barrier, and thermodynamically preferred *CH2CHO-to-*CH3CHO conversion. As a result, a high partial current density of ∼20.7 mA cm–2 and a Faraday efficiency of 46% for C2H5OH are delivered at −1.2 V vs reversible hydrogen electrode in an H-cell containing a 0.1 M KHCO3 solution. This work proposes an efficient strategy for the high-yield CO2-to-C2H5OH conversion, emphasizing the promise for the industrial production of alcohol and related products from CO2.