Insight into the Electrochemical CO 2 -to-Ethanol Conversion Catalyzed by Cu 2 S Nanocrystal-Decorated Cu Nanosheets.

Ethanol (C 2 H 5 OH) is an economically ideal C 2 product in electrochemical CO 2 reduction. However, the CO 2 -to-C 2 H 5 OH conversion yield has been rather low and the underlying catalytic mechanism remains vague or unexplored in most cases. Herein, by decorating small Cu 2 S 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 Cu 0 , and a non-flat, stepped catalyst surface, leading to the promoted affinity of *CO, decreased *COCO formation barrier, and thermodynamically preferred *CH 2 CHO-to-*CH 3 CHO conversion. As a result, a high partial current density of ∼20.7 mA cm -2 and a Faraday efficiency of 46% for C 2 H 5 OH are delivered at -1.2 V vs reversible hydrogen electrode in an H-cell containing a 0.1 M KHCO 3 solution. This work proposes an efficient strategy for the high-yield CO 2 -to-C 2 H 5 OH conversion, emphasizing the promise for the industrial production of alcohol and related products from CO 2 .