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

Abstract

Novel Bi₂WO₆/BiOBr composite photocatalysts were prepared by a one-pot EG-assisted solvothermal process in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C₁₆mim]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.