Graphene sheets grafted three-dimensional BiOBr0.2I0.8 microspheres with excellent photocatalytic activity under visible light

Highlights: • Graphene sheets grafted 3D BiOBr0.2I0.8 microspheres were synthesized. • Enhanced visible light absorption was observed in BiOBr0.2I0.8/graphene composites. • Graphene acted as an electron-acceptor to hinder the charge recombination. • The resulting composites exhibited high visible light photocatalytic activity. -- Abstract: A series of graphene sheets grafted three-dimensional BiOBr0.2I0.8 microspheres with different graphene contents have been synthesized by a simple one-step solvothermal method. The BiOBr0.2I0.8 microspheres were composed of numerous nanoplates with a thickness of about 10 nm and dispersed uniformly on the surface of graphene. The assembled BiOBr0.2I0.8/graphene composites exhibited excellent photocatalytic activity in the degradation of rhodamine B (RhB) and phenol under visible light irradiation (λ > 420 nm). The optimal graphene content was found to be 10.0 wt.%, and the corresponding photocatalytic activity in degradation of RhB and phenol was 3.19 and 3.27 times that of pure BiOBr0.2I0.8, respectively. The enhanced photocatalytic activity could be attributed to more effective charge transportations and separations, larger specific surface areas and the increased light absorption. A possible photocatalytic mechanism of the BiOBr0.2I0.8/graphene composites was also proposed