Z-scheme heterojunction Ag/AgBr/Bi2MoO6 with improved visible-light-induced photocatalytic activity

A hierarchical Ag/AgBr/Bi2MoO6 heterojunction composite was prepared without the addition of any structure-directing agent via a hydrothermal synthesis combined with subsequent deposition-photoreduction. The obtained samples were characterized by X-ray diffraction, field-emission scanning electron microscopy containing an energy X-ray dispersive spectrometer, X-ray photoelectron spectroscopy, UV-visible diffuse reflectance spectroscopy and photoluminescence spectroscopy. The results demonstrate that the Ag/AgBr/Bi2MoO6 composite exhibited enhanced photocatalytic activity under visible-light irradiation for rhodamine B degradation with a rate constant of 0.180 min(-1), which was approximately 2.5 times than that of Ag/AgBr and 22.5 times as high as Bi2MoO6. In addition, the superior visible light removing efficiencies of methylene blue and colourless phenol further confirmed the broad-spectrum photocatalytic degradation abilities of the Ag/AgBr/Bi2MoO6. Moreover, based on band structure analysis and active species trapping experiments, the improved photocatalytic performance of the Ag/AgBr/Bi2MoO6 photocatalyst was ascribed to the construction of Z-scheme bridge using Ag nanoparticles, which could increase the separation efficiency of photogenerated electron-hole pairs and keep them with high reduction and oxidation capability.