Efficient degradation of RhB over GdVO4/g-C3N4 composites under visible-light irradiation

GdVO4/g-C3N4 composite photocatalysts were synthesized by a milling and heating method. The samples were characterized by X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis diffuse reflection spectroscopy (DRS). The photocatalytic activities were evaluated in the degradation of rhodamine B aqueous solution. The result shows that g-C3N4 and GdVO4 present suitable band potentials, which induces a charge transfer at the heterojunction interfaces of the two semiconductors. The recombination of photogenerated electron-hole pairs is thus retarded and, consequently, the photocatalytic activity of GdVO4/g-C3N4 composites is enhanced. The 10 wt.% GdVO4/g-C3N4 composite presents the highest photocatalytic activity of with a degradation rate of 0.0434 min(-1), which exceeded that of pure g-C3N4 by more than 3.1 times. The proposed mechanism for the enhanced visible-light photocatalytic activity of GdVO4/g-C3N4 composites was further proven by photoluminescence (PL) spectroscopy, photocurrent-time measurement, and hydroxyl radicals trapping measurement. (C) 2012 Elsevier B.V. All rights reserved.