Pulsed Electrolysis Promotes CO Reduction to Ethanol on Heterostructured CuO/Ag Catalysts.

The electrochemical conversion of carbon dioxide (CO) into ethanol with high added value has attracted increasing attention. Here, an efficient catalyst with abundant CuO/Ag interfaces for ethanol production under pulsed CO electrolysis is reported, which is composed of CuO hollow nanospheres loaded with Ag nanoparticles (named as se-CuO/Ag). The CO-to-ethanol Faradaic efficiency is prominently improved to 46.3% at a partial current density up to 417 mA cm under pulsed electrolysis conditions in a neutral flow cell, notably outperforming conventional Cu catalysts during static electrolysis. In situ spectroscopy reveals the stabilized Cu species of se-CuO/Ag during pulsed electrolysis and the enhanced adsorbed CO intermediate (CO)coverage on the heterostructured catalyst. Density functional theory (DFT) calculations further confirm that the CuO/Ag heterostructure stabilizes the CO intermediate and promotes the coupling of CO and adsorbed CH intermediate (CH). Meanwhile, the stable Cu species under pulsed electrolysis favor the hydrogenation of adsorbed HCCOH intermediate (HCCOH) to adsorbed HCCHOH intermediate (HCCHOH) on the pathway to ethanol. The synergistic effect between the enhanced generation of CO on CuO/Ag and regenerated Cu species under pulsed electrolysis steers the reaction pathway toward ethanol. This work provides some insights into selective ethanol production from CO electroreduction via combined catalyst design and non-steady state electrolysis.