Synthesis of SiO2/Graphene@TiO2 Composites for the Visible Light Photocatalytic Degradation of Wastewater

The use of TiO2/graphene composites as catalysts for photodegradation of dyes has been widely investigated. TiO2/graphene composites are usually obtained by coating TiO2 on the surface of pre-prepared graphene. However, graphene is prone to curling and stacking, which makes it difficult to uniformly coat TiO2 on its surface, resulting in poor photocatalytic performance. In this paper, a non-conventional approach to prepare TiO2/graphene nanocomposites based on the use of porous SiO2/graphene spheres as supports is presented. SiO2/graphene spheres with intercalated structure and dendritic pores were prepared as supports by a one-step hydrothermal method. Then, TiO2 was coated into the pores of SiO2/graphene spheres by sol-gel method to obtain SiO2/graphene@TiO2 composites (SGT). After 90 min of visible light irradiation, the degradation rate of RhB by SGT catalyst was 68.9 %, which was significantly higher than that of P25 by 39.3 %. A mechanism of the RhB removal by the SGT composites was proposed.