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

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.