In-Situ Immobilization of H₅PMo₁₀V₂O₄₀ on Protonated Graphitic Carbon Nitride under Hydrothermal Conditions: A Highly Efficient and Reusable Catalyst for Hydroxylation of Benzene

A novel heterogeneous catalyst was prepared by in situ immobilization of H₅PMo₁₀V₂O₄₀ (PMo₁₀V₂) on protonated g-C₃N₄ (pg-C₃N₄) under hydrothermal conditions. The results of ζ potential, PL, FT-IR, XRD, and XPS indicated that PMo₁₀V₂ was immobilized on the protonated CNC of CN heterocycles. XPS and EPR confirmed the presence of V⁴⁺ in the catalyst due to electronic interaction between PMo₁₀V₂ and pg-C₃N₄. The textural and morphology properties of the catalyst were characterized by N₂ adsorption–desorption, SEM, and TEM. PMo₁₀V₂/pg-C₃N₄ showed excellent catalytic performance with 25.8% benzene conversion and 99.7% selectivity to phenol in the hydroxylation of benzene to phenol. The excellent catalytic performance of PMo₁₀V₂/pg-C₃N₄ could be attributed to high dispersion of PMo₁₀V₂ on pg-C₃N₄, the presence of V⁵⁺/V⁴⁺ redox pairs, and the cooperative benzene-activation capability of g-C₃N₄. The PMo₁₀V₂/pg-C₃N₄ catalyst can be easily recycled without loss of activity.