Atomically dispersed cerium on copper tailors interfacial water structure for efficient CO-to-acetate electroreduction

Electrosynthesis of acetate from carbon monoxide (CO) powered by renewable electricity offers one promising avenue to obtain valuable carbon-based products but undergoes unsatisfied selectivity because of the competing hydrogen evolution reaction. We report here a cerium single atoms (Ce-SAs) modified crystalline-amorphous dual-phase copper (Cu) catalyst, in which Ce SAs reduce the electron density of the dual-phase Cu, lowering the proportion of interfacial K+ ion hydrated water (K<middle dot>H2O) and thereby decreasing the H* coverage on the catalyst surface. Meanwhile, the electron transfer from dual-phase Cu to Ce SAs yields Cu+ species, which boost the formation of active atop-adsorbed *CO (COatop), improving COatop-COatop coupling kinetics. These together lead to the preferential pathway of ketene intermediate (*CH2-C=O) formation, which then reacts with OH- enriched by pulsed electrolysis to generate acetate. Using this catalyst, we achieve a high Faradaic efficiency of 71.3 +/- 2.1% toward acetate and a time-averaged acetate current density of 110.6 +/- 2.0 mA cm-2 under a pulsed electrolysis mode. Furthermore, a flow-cell reactor assembled by this catalyst can produce acetate steadily for at least 138 hours with selectivity greater than 60%.