Catalytic CO Oxidation by Noble-Metal-Free Ni2VO4,5- Clusters: A CO Self-Promoted Mechanism.

Catalytic CO oxidation is an important model reaction in gas-phase studies to provide a clear structure-reactivity understanding in related heterogeneous catalysis, whereas CO oxidation catalyzed by noble-metal (NM) free species has been scarcely reported, and the fundamental aspects are elusive. Herein a CO self-promoted mechanism of catalytic CO oxidation by O2 mediated with the Ni2VO4,5- clusters was experimentally identified and theoretically rationalized. The catalysis was characterized by mass spectrometry and quantum chemistry calculations. Ni2VO5- can oxidize CO to generate an oxygen-deficient product Ni2VO4-, which can only adsorb CO to give rise to Ni2VO4CO-, and the oxidative reactivity of Ni2VO4- can be boosted by the adsorbed  CO. This finding reinforces the significance that the attached CO can modify the electronic structure of the Ni2 unit in Ni2VO4CO- and make the Ni2 unit behave like NM atoms to store the released electrons in an oxygen atom transfer process.