The effect of iron doping on the photocatalytic activity of a Bi2WO6–BiVO4 composite

Visible-light-driven Fe-doped Bi2WO6–BiVO4 composites have been synthesized via a hydrothermal method with varying nominal iron contents in the range of 0.5–5.0 mol%. The physicochemical properties of the obtained materials were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET)-specific surface area, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), and photoluminescence (PL) techniques. Methylene blue (MB) as probe pollutant was adopted to investigate the photocatalytic activity of all samples under visible light irradiation. The Fe-doped Bi2WO6–BiVO4 composites showed an enhanced photocatalytic activity for the degradation of MB under visible light, which was attributed to the iron ions acting as good electron and hole traps for facilitating the separation of charge carriers. Simultaneously, the high stability of the sample was also investigated by five successive photodegradation tests of MB under visible light. The relationship between the photocatalytic activities and the structures of Fe-doped Bi2WO6–BiVO4 composites was discussed. The possible photocatalytic mechanism of the composites was proposed to guide the further improvement of their photocatalytic performance.