Synergistic Catalysis of Fe₂O₃ Nanoparticles on Mesoporous Poly(ionic liquid)-Derived Carbon for Benzene Hydroxylation with Dioxygen

Carbon-supported ferric oxide nanoparticles (Fe₂O₃ NPs) were constructed via directly carbonizing mesoporous poly(ionic liquid) with [Fe(CN)₆]^3- anions, which was prepared through the free-radical self-polymerization of ionic liquid monomer 1-allyl-3-vinylimidazolium chloride in a soft-template route and successive ion exchange with potassium ferricyanide. The unique mesoporous ionic networks enabled the molecular dispersion of ferric precursors and therefore resulted in highly dispersed Fe₂O₃ NPs on carbon. The catalyst exhibited high yield, remarkable turnover number, and good reusability in the reductant-free aerobic oxidation of benzene to phenol with O₂. The synergistic effect of Fe₂O₃ NPs and carbon accounted for the high performance. This work delivered the first efficient and environmentally friendly heterogeneous catalyst for reductant-free benzene hydroxylation with O₂.