Graphene-spindle shaped TiO₂ mesocrystal composites: Facile synthesis and enhanced visible light photocatalytic performance

Graphene (GR)-TiO₂ mesocrystal composites were prepared by a facile template-free process based on the combination of sol-gel and solvothermal methods, and were characterized using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-vis DRS), nitrogen absorption and electron spin resonance (ESR). Visible light photocatalytic performance of GR-TiO₂ composites was evaluated for photocatalytic degradation of organic dye Rhodamine B. It was found that the amount of graphene oxide (GO) added obviously affects morphologies of TiO₂ mesocrystals and photocatalytic activities of as-prepared nanocomposites. Composites prepared in the presence of different amounts of GO all exhibit higher photocatalytic activity than pure TiO₂ mesocrystals and P25, the composite obtained by using 20mg GO presents the most uniform TiO₂ mesocrystals in the composite and shows the highest photocatalytic efficiency. The mechanism for the generation of TiO₂ mesocrystals in the GR-TiO₂ composite is proposed and possible reasons for the enhancement in visible light photocatalytic efficiency are also discussed.