Spectroscopic Insights Into the Role of the Coverage of *CO and *H on Bifurcation of Ethylene and Ethanol Pathways in Carbon Dioxide Electroreduction

ABSTRACT As key reaction intermediates involved in the electroreduction of carbon dioxide, *CO and *H (* represents active center) prove to be critical in regulating the selectivity toward different carbonaceous products. However, how the coverage of *H and *CO affects the selectivity of ethylene and ethanol remains unclear. In this work, we judiciously control the coverage of *CO or *H intermediates by introducing foreign metal into Cu nanoparticles, with the synthesis of four copper‐based bimetallic catalysts, including CuAg, CuZn, CuCo, and CuPd. Four catalysts, together with Cu nanoparticles, are subjected to the electrochemical reduction of carbon dioxide in an H‐cell. The CuZn catalyst is identified as the most effective catalyst for C─C coupling, exhibiting a Faradaic efficiency of 34.5% for C 2+ products at −1.09 V versus RHE and a current density of −30.4 mA cm −2 . In contrast, CuPd catalyst inclines to catalyze C─C coupling toward ethanol, with an FE ethanol /FE ethylene ratio reaching up to 1.15. The coverage of key intermediates is investigated through in situ Raman spectroscopy. The doping of Ag and Zn metals can enhance the adsorption of *CO on the catalyst, while the doping of Co and Pd metals can enhance the adsorption of *H on the catalyst. Hence, the increased *CO coverage on Ag‐ and Zn‐doped CuNP promotes C 2+ generation, and the increased *H coverage of Co‐ and Pd‐doped CuNPs enhances the C 2 H 5 OH/C 2 H 4 ratio.