Constructing Defective Co3V2O8 Hexagonal Prism for Solvent-free Selective Oxidation of Cyclohexane: Strategy of Ionic Liquid Mediation

Oxygenvacancies (OVs) engineering is essential in the regulationof the structure and properties of the catalysts for selective oxidation.In this work, the strategy of ionic liquid (IL) mediation was successfullydeveloped in constructing the OV-rich defective Co3V2O8 (CVO), exhibiting excellent performance in cyclohexaneoxidation. Coupling the prepotency of the heating treatment, ILs constructedoptimal [Bmim]-[Ac]-CVO-700 possesses the highest OV concentrationand catalytic activity with 12.7% cyclohexane conversion accompaniedby 89.6% KA oil (cyclohexanol and cyclohexanone) selectivity. Experimentalinvestigation reveals that ILs not only regulates the morphology structureas structure-directing agents but also benefits the formation of OVsthrough coordination with the Co2+ and V5+.The redox cycle between Co3+/Co2+ and V5+/V4+ was accelerated via the constructed OVs,enhancing the activation of substrates and the transfer of electrons.The distinguished performance is attributed to the rich OVs, porousstructure, and synergistic effect between the active metals. The structure-activityrelationship between OVs concentration and cyclohexane conversionfurther indicated that OVs facilitate the essential steps for thegeneration of targeted products. The possible reaction pathway ofcyclohexane oxidation over the OV-rich CVO catalyst was also suggestedregarding the radical trapping experiment. This design not only presentsa facile and effective strategy for constructing OVs using ILs butalso provides an in-depth insight into OV-rich mixed metal oxidesin selective oxidation.