Synthesis, characterization and photocatalytic activity of AgBr/H 2WO 4 composite photocatalyst

Abstract

A new composite photocatalyst AgBr/H 2WO 4 was prepared by loading H 2WO 4 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/H 2WO 4 under visible-light irradiation ( λ > 420 nm). The photocatalytic results show that the AgBr/H 2WO 4 composite could degrade MO and RhB efficiently and had much higher photocatalytic activity than AgBr or H 2WO 4. X-ray photoelectron spectroscopy (XPS) suggests that AgBr/H 2WO 4 transformed to be Ag/AgBr/H 2WO 4 system while remained good photocatalytic 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 2 − played the major roles for the dye degradation while OH 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 H 2WO 4, as well as the surface plasmon resonance of Ag nanoparticles formed on AgBr particles during the photocatalytic reaction process.