Fabrication and enhanced visible-light photocatalytic activities of BiVO4/Bi2WO6 composites

Abstract

BiVO₄/Bi₂WO₆ composite photocatalysts were synthesized by coupling a homogeneous precipitation method with hydrothermal techniques. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), UV-Vis diffusion absorption spectroscopy (DRS) and photoluminescence (PL), respectively. The photocatalytic activities were evaluated by the degradation of methyl blue (MB) under visible-light irradiation. The results reveal that BiVO₄/Bi₂WO₆ composites exhibit higher photocatalytic activities than either pure Bi₂WO₆ or BiVO₄. The 0.3BiVO₄:0.7Bi₂WO₆ sample shows the best photocatalytic performance. The enhancement of photocatalytic activity is attributed to the improvement of light absorption, the excellent adsorbability, the narrow band gap and increasing separation rate of photo-generated charge carriers. The possible photocatalytic mechanism is discussed on the basis of the band structures of BiVO₄ and Bi₂WO₆.