Ag Single Atoms Anchored on CeO with Interfacial Oxygen Vacancies for Efficient CO Electroreduction.

Ag single-atom catalysts (SACs) have great potential in selective electrocatalysis of the CO reduction reaction (CORR) to CO, while it is still a challenge to achieve high current density and high atom efficiency simultaneously. Here, we present a new and simple adsorption-reduction method to prepare Ag SACs supported on CeO (Ag/CeO). It is found that Ag single atoms are anchored on CeO through strong metal-support interaction (SMSI), and each Ag atom is accompanied with three interfacial oxygen vacancies. This Ag/CeO exhibits high performance in the electrocatalytic CORR with a high CO faradaic efficiency (FE) of >95% under a wide potential range. The turnover frequency (TOF) value can reach 50,310 h at FE = 99.5% in H-cells. Notably, Ag/CeO achieves an industrial-grade current density of 403 mA cm with a high FE of 97.2% in flow cells. Experimental results combined with density functional theory calculation revealed that this superior performance was mainly ascribed to the existence of interfacial oxygen vacancies, which lead to the formation of Ag-O-Ce atomic interfaces, and activates the Ce-O structures as the synergistic active center of Ag, thus promoting CO adsorption and activation and reducing the reaction potential barrier of *COOH-to-*CO.