Over 70 % Faradaic Efficiency for CO 2 Electroreduction to Ethanol Enabled by Potassium Dopant-Tuned Interaction between Copper Sites and Intermediates.

It is highly desired yet challenging to steer the CO 2 electroreduction reaction (CO 2 ER) toward ethanol with high selectivity, for which the evolution of reaction intermediates on catalytically active sites holds the key. Herein, we report that K doping in Cu 2 Se nanosheets array on Cu foam serves as a versatile way to tune the interaction between Cu sites and reaction intermediates in CO 2 ER, enabling highly selective production of ethanol. As revealed by characterization and simulation, the electron transfer from K to Se can stabilize Cu I species which facilitate the adsorption of linear *CO L and bridge *CO B intermediates to promote C-C coupling during CO 2 ER. As a result, the optimized K 11.2% -Cu 2 Se nanosheets array can catalyze CO 2 ER to ethanol as a single liquid product with high selectivity in a potential area from -0.6 to -1.2 V. Notably, it offers a Faradaic efficiency of 70.3 % for ethanol production at -0.8 V with as is stable for 130 h.