Synthesis, characterization and photocatalytic activity of AgBr/H2WO4 composite photocatalyst

A new composite photocatalyst AgBr/H2WO4 was prepared by loading H2WO4 on AgBr substrate via deposition-precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and UV-vis diffuse reflectance spectroscopy (DRS). Photocatalytic degradation of methyl orange (MO) and rhodamine B (RhB) was carried out to evaluate the photocatalytic activity of AgBr/H2WO4 under visible-light irradiation (lambda > 420 nm). The photocatalytic results show that the AgBr/H2WO4 composite could degrade MO and RhB efficiently and had much higher photocatalytic activity than AgBr or H2WO4. X-ray photoelectron spectroscopy (XPS) suggests that AgBr/H2WO4 transformed to be Ag/AgBr/H2WO4 system while remained good phorocatalytic activity after 5 times of cycle experiments. In addition, the quenching effect was examined in the photocatalytic reaction process of MO and RhB, respectively. Active h(+), Br-0 and the resulting O-center dot(2) played the major roles for the dye degradation while (OH)-O-center dot was verified to be insignificant. The high photocatalytic activity and good stability are closely related to the efficient electron-hole pairs separation derived from the matching band potentials between AgBr and H2WO4, as well as the surface plasmon resonance of Ag nanoparticles formed on AgBr particles during the photocatalytic reaction process. (C) 2011 Elsevier B.V. All rights reserved.