Hierarchically structured α-Fe2O3/Bi2WO6 composite for photocatalytic degradation of organic contaminants under visible light irradiation

Abstract

The α-Fe₂O₃/Bi₂WO₆ composite with a sphere-like hierarchical structure assembled by nanosheets was synthesized by a one-step hydrothermal route without any templates or surfactants. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectrum (UV–vis DRS), Fourier transform infrared (FT–IR) spectrum, X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmet–Teller (BET) analysis. The BET specific surface area of the hierarchically structured α-Fe₂O₃/Bi₂WO₆ composite is 61.7 m² g⁻¹, which is much higher than that (3.5 m² g⁻¹) of the pure Bi₂WO₆. The hierarchically structured α-Fe₂O₃/Bi₂WO₆ composite exhibited a strong adsorption capability and a higher visible light photocatalytic activity than the pure Bi₂WO₆ for the photocatalytic degradation of acid red G dye or Rhodamine B (RhB) dye in aqueous solution under visible-light irradiation (>420 nm). The composite still showed the high photocatalytic activity after four reaction cycles. On the basis of the experimental results and calculated energy band positions, the enhanced photocatalytic activity of the composite can be attributed to the hierarchical structure and the coupling effect of α-Fe₂O₃ and Bi₂WO₆ in the composite.