Synthesis of Ag/TiO2/graphene and its photocatalytic properties under visible light

A composite photocatalyst containing silver (Ag) nanoparticles, titanium oxide (TiO2) and graphene, was synthesized by a combined sol-gel/solvothermal method in ethanol solution. The generation of Ag nanoparticles, formation of reduced graphene oxide (rGO) and crystallization of TiO2 were achieved simultaneously with ethanol acting as both a solvent and a reductant for rGO reduction. The yielded ternary nanocomposite possessed the merits of graphene, TiO2 and Ag nanoparticles. The rGO inhibited the charge recombination and enhanced the electron-hole separation of TiO2 through combining TiO2 and Ag nanoparticles as a potent conductor. A surface plasmon resonance effect of the incorporated Ag nanoparticles led to an increase in light absorption. As such, the resulting composite exhibited a large superficial area and an improved photocatalytic activity to decompose methylene blue compounds under visible light irradiation. Experimental results showed that as-prepared Ag/TiO2/rGO possessed an excellent photocatalytic activity for degrading MB more than 79% under visible light irradiation. As to P25, Ag/TiO2 and TiO2/rGO photocatalysts, only 35%, 38%, 53% MB was removed after 4 h irradiation respectively.