Ternary mesoporous WO3/Mn3O4/N-doped graphene nanocomposite for enhanced photocatalysis under visible light irradiation

Abstract

A novel ternary nanocomposite comprising mesoporous WO₃, Mn₃O₄ nanoparticles and N-doped graphene was prepared by a one-pot deposition method. The nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The results demonstrated that the Mn₃O₄ nanoparticles had been successfully hybridized with the mesoporous WO₃ and the WO₃/Mn₃O₄ hybrid was well dispersed on the surface of N-doped graphene with superior interactions. The nanocomposite exhibits higher photocatalytic activity for water oxidation than the individual mesoporous WO₃ and WO₃/Mn₃O₄ catalysts. The amount of oxygen evolution from the optimized heterostructural photocatalyst (1.5 wt% Mn₃O₄ and 2 wt% N-doped graphene) was 294 μmol g⁻¹, which was about 3.6 times as high as that from m-WO₃. The heterostructure formed between Mn₃O₄ and m-WO₃ enhances photogenerated electron/hole transfer and restrains the recombination of charges greatly. N-doped graphene in the nanocomposite acting as an excellent electron acceptor and mediator also contributes to the increase in photocatalytic performance by promoting the separation and transfer of photogenerated charges. This study suggests a promising method to enhance photocatalytic activity by combining the heterostructural WO₃/Mn₃O₄ hybrid with graphene in a ternary system.