Synthesis of novel and stable g-C3N4-Bi2WO6 hybrid nanocomposites and their enhanced photocatalytic activity under visible light irradiation.

Graphitic carbon nitride (g-C3N4) nanosheets with a thickness of only a few nanometres were obtained by a facile deammoniation treatment of bulk g-C3N4 and were further hybridized with Bi2WO6 nanoparticles on the surface via a solvothermal method. The composite photocatalysts were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflection spectroscopy and X-ray photoelectron spectroscopy (XPS). The HR-TEM results show that the nano-sized Bi2WO6 particles were finely distributed on g-C3N4 sheet surface, which forms heterojunction structure. The UV-vis diffuse reflectance spectra (DRS) show that the absorption edge of composite photocatalysts shifts towards lower energy region in comparison with those of pure g-C3N4 and Bi2WO6. The degradation of methyl orange (MO) tests reveals that the optimum activity of 8 : 2 g-C3N4-Bi2WO6 photocatalyst is almost 2.7 and 8.5 times higher than those of individual g-C3N4 and Bi2WO6. Moreover, the recycle experiments depict high stability of the composite photocatalysts. Through the study of the influencing factors, a possible photocatalytic mechanism is proposed. The enhancement in both photocatalytic performance and stability was caused by the synergistic effect, including the effective separation of the photogenerated electron-hole pairs at the interface of g-C3N4 and Bi2WO6, the smaller the particle size and the relatively larger specific surface area of the composite photocatalyst.