Facile synthesis and improvement of photocatalytic efficiency of FeVO4/Bi4O5Br2 Heterojunction

Abstract

Semiconductor-mediated photocatalysis is a promising solution for wastewater remediation. Bismuth-rich oxybromide with a chemical formula of Bi4O5Br2 has been reported as a good candidate for organic pollutant degradation and transformation of inorganic species under visible light irradiation. However, the photocatalytic efficiency of Bi4O5Br2 is still limited by high recombination rate of photogenerated electron-hole pairs due to its narrow band gap (2.56 eV). Fabrication of a semiconductor-semiconductor heterojunction is a promising route to resolve this limitation. In this research, the visible light-driven photocatalytic activity of the Bi4O5Br2 photocatalyst was enhanced by combining with FeVO4 to form FeVO4/Bi4O5Br2 heterojunction. Herein, the Bi4O5Br2 and FeVO4 were separately synthesized by cyclic microwave irradiation method. Physiochemical and optical properties of the synthesized photocatalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). Effect of FeVO4 contents in the FeVO4/Bi4O5Br2 composites was 1% by weight which 95% of hexavalent chromium (Cr6t), 98% of rhodamine B (RhB), 90% of bisphenol A (BPA), and 88% of tetracycline (TC) were removed under visible light irradiation. The FeVO4/Bi4O5Br2 composite was effective in the reuse, and exhibited good stability after four times of usage. Charge transfer mechanism during the photocatalytic process was proposed based on the reactive species trapping experiments, along with the consideration of the reduction potentials of reactive oxygen species and band potential of the FeVO4/Bi4O5Br2 heterojunction.