Catalytic CO Oxidation by Noble-Metal-Free Ni ₂ VO _4,5 ^- 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 O ₂ mediated with the Ni ₂ VO _4,5 ^- clusters was experimentally identified and theoretically rationalized. The catalysis was characterized by mass spectrometry and quantum chemistry calculations. Ni ₂ VO ₅ ^- can oxidize CO to generate an oxygen-deficient product Ni ₂ VO ₄ ^- , which can only adsorb CO to give rise to Ni ₂ VO ₄ CO ^- , and the oxidative reactivity of Ni ₂ VO ₄ ^- can be boosted by the adsorbed CO. This finding reinforces the significance that the attached CO can modify the electronic structure of the Ni ₂ unit in Ni ₂ VO ₄ CO ^- and make the Ni ₂ unit behave like NM atoms to store the released electrons in an oxygen atom transfer process.