Oil-in-water self-assembled Ag@AgCl QDs sensitized Bi2WO6: Enhanced photocatalytic degradation under visible light irradiation

Quantum dots (QDs) Ag@AgCl decorated on the surface of flower-like Bi2WO6 (hereafter designated Ag@AgCl/Bi2WO6) were prepared via a facile oil-in-water self-assembly method. The photocatalysts were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray fluorescence spectrometer (XRF) etc. The characterization results indicated that QDs Ag@AgCl was observed to be evenly dispersed on the surface of Bi2WO6, and was approximately 10-20 nm in size. Ag@AgCl/Bi2WO6 composites exhibited excellent UV-vis absorption, due to quantum dimension effect of Ag@AgCl QDs, the surface plasmonic resonance (SPR) of Ag nanoparticles and the special flower-like structure of Bi2WO6. The photo-electrochemical measurement verified that the suitable band potential of Ag@AgCl and Bi2WO6 and the existence of metal Ag resulted in the high efficiency in charge separation of the composite. The photocatalytic activities of the Ag@AgCl/Bi2WO6 samples were examined under visible light irradiation for the degradation of Rhodamine B (RhB). The composite presented excellent photocatalytic activity due to the synergetic effect of Bi2WO6, AgCl, and Ag nanoparticles. The Ag@AgCl(20 wt.%)/Bi2WO6 sample exhibited the best photocatalytic activity, degrading 97.61% RhB after irradiation for 2 h, which was, respectively, 1.33 times and 1.32 times higher than that of Ag@AgCl and Bi2WO6 photocatalyst. Meanwhile, phenol was degraded to further prove the degradation ability of Ag@AgCl/Bi2WO6. Additionally, studies performed using radical scavengers indicated that O-2(-center dot), h(+) and Cl-0 acted as the main reactive species. Based on above, a photocatalytic mechanism for organics degradation over Ag@AgCl/Bi2WO6 was proposed. (C) 2014 Elsevier B.V. All rights reserved.