Novel 3D flowerlike BiOCl0.7Br0.3 microspheres coupled with graphene sheets with enhanced visible-light photocatalytic activity for the degradation of rhodamine B

Highly efficient visible-light-driven 3D flowerlike BiOCl0.7Br0.3 microspheres coupled with graphene sheets with different graphene contents have been synthesized by a facile solvothermal process. The as-prepared samples were characterized by power X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption analysis and UV-vis diffuse reflectance spectra (DRS). Characterization results showed BiOCl0.7Br0.3 microspheres were composed of numerous nanoplates with a thickness of about 20 nm and dispersed uniformly on the surface of graphene. Moreover, the photocatalytic activities of these BiOCl0.7Br0.3/graphene composites under visible-light irradiation (λ>420 nm) were evaluated by the degradation of rhodamine B (RhB). The results indicate all BiOCl0.7Br0.3/graphene composites exhibited much higher photocatalytic activities than pristine BiOCl0.7Br0.3, pure BiOBr and BiOCl, and the highest activity was reached by the BiOCl0.7Br0.3/graphene composite photocatalyst with 10 wt% of graphene. The enhanced photocatalytic activity could be largely ascribed to more effective charge transportations and separations, larger BET surface areas and the increased light absorption. In addition, a possible photocatalytic mechanism of the BiOCl0.7Br0.3/graphene composites on basis of the experimental results was also proposed.