Synthesis and photocatalytic properties of visible light responsive La/TiO2-graphene composites

La/TiO2-graphene composites used as photocatalyst were prepared by two-step hydrothermal method. The as-prepared composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The results of optical properties of La/TiO2-graphene composites exhibit extended light absorption in visible-light region and possess better charge separation capability as compared to pure TiO2. The photocatalytic activity measurement demonstrate that La/TiO2-graphene composites exhibited an enhanced photocatalytic activity for methylene blue (MB) degradation under visible-light irradiation compared to pure TiO2, which was attributed to greater adsorptivity of dyes, extended light absorption and increased charge separation efficiency due to excellent electrical properties of graphene and the large surface contact between graphene and La/TiO2 nanoparticles.