2D/2D Bi2MoO6/g-C3N4 S-scheme heterojunction photocatalyst with enhanced visible-light activity by Au loading

A novel 2D/2D BiMoO/g-CNstep-scheme(S-scheme) composite by loading Au as cocatalyst was successfully fabricated using a photoreduction and hydrothermal route. The obtained BiMoO/g-CN/Au photocatalysts were characterized by X-ray diffraction(XRD), transmission electron microscope(TEM),X-ray photo-electron spectroscopy(XPS), UV–vis diffuse reflectance spectra(UV–vis), Fourier transform infrared spectroscopy(FTIR), photoluminescence(PL), photocurrent response(I-t), and electrochemical impedance spectroscopy(EIS). The HRTEM images revealed that an intimate interface in composites were formed. The optimum photocatalytic activity of Rhodamine B degradation over BiMoO/g-CN/Au was about 9.7 times and 13.1 times as high as those of BiMoOand g-CN, respectively. The notably improved photocatalytic activity of BiMoO/g-CN/Au could be mainly ascribed to the abundant active sites and the enhanced separation efficiency of photogenerated carriers in BiMoO/g-CNS-scheme system. Notably, Au nanoparticles could act as a co-catalyst to further promote electron transfer and separation from the conduction band of g-CN. Additionally, a possible step-scheme photocatalytic reaction mechanism of Rh B degradation over BiMoO/g-CN/Au was tentatively proposed. PL and transient photocurrent analysis implied that BiMoO/g-CN/Au photocatalysts possessed the lower recombination rate of photogenerated carriers compared with pure BiMoOand g-CN, respectively. The present work is expected to provide useful information in designing 2D/2D S-scheme heterojunction photocatalysts.