Synthesis and photocatalytic performance of Bi2WO6/BiOX (X=Cl, Br, I) composites for RhB degradation under visible light

The present study examined the effects of adding bismuth oxyhalides, BiOCl, BiOBr and BiOI, on the photocatalytic properties of Bi2WO6. The samples were synthesized using a simple one-stage hydrothermal method. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), diffused reflectance spectroscopy (DRS) and the nitrogen absorption/desorption technique. The activity of the products on the photocatalytic degradation of an aqueous Rhodamine B (RhB) solution was then investigated under visible light irradiation. The results showed the higher photocatalytic efficiency of the hybrid Bi2WO6/BiOBr sample compared to that of other compounds, as approximately 97% of RhB molecules were degraded after 80 minutes of irradiation in the presence of this sample. Under the same conditions, pure Bi2WO6 and hybrid samples of Bi2WO6/BiOCl and Bi2WO6/BiOI, respectively, degraded 40%, 60% and 20% of dye molecules in the solution. The better performance of this sample compared to that of the others can be explained by its larger effective surface area and the strong interaction between Bi2WO6 and BiOBr. Furthermore, a test conducted to determine active species in photocatalytic reactions showed that superoxide radicals played the main role in the degradation of RhB molecules by hybrid Bi2WO6/BiOBr photocatalyst.