Pulsed Electrolysis Promotes CO2 Reduction to Ethanol on Heterostructured Cu2O/Ag Catalysts.

ABSTRACT

The electrochemical conversion of carbon dioxide (CO2) into ethanol with high added value has attracted increasing attention. Here, an efficient catalyst with abundant Cu2O/Ag interfaces for ethanol production under pulsed CO2 electrolysis is reported, which is composed of Cu2O hollow nanospheres loaded with Ag nanoparticles (named as se-Cu2O/Ag). The CO2-to-ethanol Faradaic efficiency is prominently improved to 46.3% at a partial current density up to 417 mA cm-2 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-Cu2O/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 Cu2O/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 Cu2O/Ag and regenerated Cu+ species under pulsed electrolysis steers the reaction pathway toward ethanol. This work provides some insights into selective ethanol production from CO2 electroreduction via combined catalyst design and non-steady state electrolysis.