Facile fabrication of the visible-light-driven Bi2WO6/BiOBr composite with enhanced photocatalytic activity

Novel Bi2WO6/BiOBr composite photocatalystswere prepared by a one-pot EG-assisted solvothermal process in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C(16)mim]Br). Multiple techniques, such as X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflection spectroscopy (DRS), photoluminescence (PL), photocurrent and electrochemical impedance spectroscopy (EIS) were applied to investigate the structures, morphology and photocatalytic properties of as-prepared samples. Compared with bare Bi2WO6 and BiOBr, the Bi2WO6/BiOBr composites exhibited significantly enhanced photocatalytic activity for rhodamine B (RhB) degradation under visible light irradiation. The 50 at% Bi2WO6/BiOBr showed the highest photocatalytic activity under visible light irradiation, which was about 26.6 times and 1.8 times than that of the bare Bi2WO6 and BiOBr, respectively. The Bi2WO6/BiOBr composites also exhibited enhanced photocatalytic activity for bisphenol A (BPA) and methylene blue (MB) degradation under visible light irradiation. The results of PL, photocurrent and EIS indicated that Bi2WO6 and BiOBr could combine well to form a heterojunction structure which facilitated electron-hole separation, and led to the increasing photocatalytic activity. On the basis of the experimental results and estimated energy band positions, the mechanism of enhanced photocatalytic activity was proposed.