Facile Synthesis of Vanadium Oxide/Reduced Graphene Oxide Composite Catalysts for Enhanced Hydroxylation of Benzene to Phenol

The vanadium oxide/reduced graphene oxide (VOx/RGO) composites have been prepared by a simple solvothermal method with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB). The microstructure and morphology of the resultant VOx/RGO composites have been well characterized. The VOx nanoparticles are highly dispersed on the RGO sheets with a particle size of about 25 nm. When used as hydroxylation catalysts, the VOx/RGO composites are more efficient than individual RGO and vanadium oxide catalysts. The enhanced catalytic performance may be related to not only the well dispersed VOx active species, but also the hydrophobic surface and huge π-electron system of RGO for the adsorption and activation of benzene. In addition, the effects of calcination conditions on the microstructure and catalytic properties of VOx/RGO composites have also been investigated. The uniform VOx nanoparticles on the separated RGO sheets show highly efficient catalytic performance, while the formation of aggregated HxV2O5 and bulk V2O5 species along with the destruction of RGO sheets are poor for the hydroxylation of benzene. Up to 17.4% yield of phenol is achieved under the optimized catalytic reaction conditions.