Turning the Selectivity of CO Electroreduction from Acetate to Ethanol by Alloying FCC-Phased Cu with Atomically Dispersed Mn Atoms.

The predominant product of CO electroreduction (COER) is often acetate, with the Faradaic efficiency (FE) for ethanol usually falling below 50%. Herein, we propose a unique strategy to enhance product selectivity in COER, shifting it from acetate predominance toward ethanol generation via alloying atomic manganese (Mn) atoms with a face-centered cubic (FCC) copper (Cu) catalyst. By optimizing the atomic ratio of Mn to Cu, we observe an impressive enhancement of 8.8-fold for the ethanol-to-acetate FE ratio in the optimal Mn3Cu97 alloy compared to unalloyed FCC-phase Cu. Mn3Cu97 demonstrates a remarkable ethanol FE of nearly 70% at a high current density of 600 mA cm-2 in a membrane electrode assembly electrolyzer. Further theoretical analysis reveals that atomically dispersed Mn atoms generate synergistic active sites and modulate the adsorption strength of critical intermediates relevant to ethanol synthesis, thereby facilitating the transition from the acetate pathway to the ethanol pathway.