Ag2S sensitized mesoporous Bi2WO6 architectures with enhanced visible light photocatalytic activity and recycling properties

Abstract

To harvest solar energy more efficiently, novel Ag₂S/Bi₂WO₆ heterojunctions were synthesized by a hydrothermal route. This novel photocatalyst was synthesized by impregnating Ag₂S into a Bi₂WO₆ semiconductor by a hydrothermal route without any surfactants or templates. The as prepared structures were characterized by multiple techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmet–Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), UV-vis diffuse reflection spectroscopy (DRS) and photoluminescence (PL). The characterization results suggest mesoporous hierarchical spherical structures with a high surface area and improved photo response in the visible spectrum. Compared to bare Bi₂WO₆, Ag₂S/Bi₂WO₆ exhibited much higher photocatalytic activity towards the degradation of dye Rhodamine B (RhB). Although silver based catalysts are easily eroded by photogenerated holes, the Ag₂S/Bi₂WO₆ photocatalyst was found to be highly stable in the cyclic experiments. Based on the results of BET, Pl and DRS analysis, two possible reasons have been proposed for the enhanced visible light activity and stability of this novel photocatalyst: (1) broadening of the photoabsorption range and (2) efficient separation of photoinduced charge carriers which does not allow the photoexcited electrons to accumulate on the conduction band of Ag₂S and hence prevents the photocorrosion.