Selective Electrosynthesis of Ethanol via Asymmetric C–C Coupling in Tandem CO2 Reduction

Selective electroreduction of CO2 to ethanol has economic value and environmental significance. However, the activity and selectivity of CO2 reduction toward ethanol are still low due to the sluggish kinetics of C–C coupling and the intense competition of hydrocarbon production. Herein, we report a layered tandem catalyst consisting of Cu nanosheets with a Cu(111)-oriented surface and Ag nanoparticles, which can effectively shift the selectivity from hydrocarbons to ethanol. The Faradaic efficiency of ethanol was improved from less than 30% on bare Cu(111) to 56.5 ± 2.6% on the layered Cu/Ag tandem catalysts, with a partial current density of 356.7 ± 9.5 mA cm–2. In situ Raman spectroscopy results and density functional theory calculations suggest that the high selectivity toward ethanol can be attributed to the asymmetric *CH2–CO coupling mechanism, which is facilitated by the selective generation of *CH2 species on (111)-facet-exposed Cu nanosheets and the high local CO concentration supplied by the Ag catalyst.