Oxygen Doping Induced by Nitrogen Vacancies in Nb 4 N 5 Enables Highly Selective CO 2 Reduction

Surface vacancy engineering holds great promise for boosting the electrocatalytic activity for CO 2 reduction reaction; however, the vacancies are generally unstable and may degrade into the inactive phase during electrolysis. Stabilizing the vacancy‐enriched structure by heteroatoms can be an effective strategy to get a robust and active catalyst. Herein, a nitrogen‐vacancy enriched Nb 4 N 5 on N‐doped carbons is constructed, which is thereafter stabilized by a self‐enhanced oxygen doping process. This oxygen‐doped complex is used as an effective CO 2 catalyst, which exhibits a maximum CO Faradaic efficiency of 91% at −0.8 V (vs reversible hydrogen electrode, RHE) and long‐term stability throughout 30 h of electrocatalysis. Density function theory calculations suggest that the incorporation of oxygen in Nb 4 N 5 facilitates the formation of *COOH and thus promotes the CO 2 reduction.