Bangde Luo

Visible light photocatalytic activity enhancement and mechanism of AgBr/Ag3PO4 hybrids for degradation of methyl orange

Novel AgBr/Ag(3)PO(4) hybrids were synthesized via an in situ anion-exchange method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS) and UV-vis diffuse reflectance spectroscopy (DRS). Under visible light (λ>420 nm), AgBr/Ag(3)PO(4) degraded methyl orange (MO) efficiently and displayed much higher photocatalytic activity than that of pure AgBr or Ag(3)PO(4). X-ray photoelectron spectroscopy (XPS) suggests that AgBr/Ag(3)PO(4) transformed to be Ag@AgBr/Ag(3)PO(4)@Ag system while remained good photocatalytic activity after 5 times of cycle experiments. In addition, the quenching effects of different scavengers proved that reactive OH and h(+) played the major role for the MO degradation. The photocatalytic activity enhancement of AgBr/Ag(3)PO(4) is closely related to the efficient separation of electron-hole pairs derived from the matching band potentials between AgBr and Ag(3)PO(4), as well as the good electron trapping role of Ag nanoparticles in situ formed on the surfaces of AgBr and Ag(3)PO(4) particles during the photocatalytic reaction.

Photocatalytic activity of novel AgBr/WO3 composite photocatalyst under visible light irradiation for methyl orange degradation.

A novel AgBr/WO(3) composite photocatalyst was synthesized by loading AgBr on WO(3) substrate via deposition-precipitation method and characterized by XRD, SEM and DRS. The as-prepared AgBr/WO(3) was composed of monoclinic WO(3) substrate and face-centered cubic AgBr nanoparticles with crystalline sizes less than 56.8 nm. AgBr/WO(3) had absorption edge at about 470 nm in the visible light region. The optical AgBr content in AgBr/WO(3) was 0.30:1 (Ag/W) at the corresponding apparent rate, k(app), of 0.0160 min(-1) for MO degradation. The highest k(app) was 0.0216 min(-1) for 4 g/L catalyst. The OH acted as active species. Addition of H(2)O(2) within 0.020 mmol/L can efficiently trap electrons to generate more OH and further improved photocatalytic activity of AgBr/WO(3).