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 (Cu^δ+), abundant interfaces between Cu^δ+ 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.