Factors Determining the Selectivity of NO Reduction Catalyzed by Copper‐Vanadium Oxide Cluster Anions Cu2VO3−5−

Abstract Catalytic NO reduction by CO is imperative to satisfy the increasingly rigorous emission regulations. Identifying the structural characteristic of crucial intermediate that governs the selectivity of NO reduction is pivotal to having a fundamental understanding on real‐life catalysis. Herein, benefiting from the state‐of‐the‐art mass spectrometry, we demonstrated experimentally that the Cu 2 VO 3–5 − clusters can mediate the catalysis of NO reduction by CO, and two competitive channels to generate N 2 O and N 2 can co‐exist. Quantum‐chemical calculations were performed to rationalize this selectivity. The formation of the ONNO unit on the Cu 2 dimer was demonstrated to be a precursor from which two pathways of NO reduction start to emerge. In the pathway of N 2 O generation, only the Cu 2 dimer was oxidized and the VO 3 moiety functions as a “support”, while both moieties have to contribute to anchor oxygen atoms from the ONNO unit and then N 2 can be generated. This finding displays a clear picture to elucidate how and why the involvement of VO 3 “support” can regulate the selectivity of NO reduction.