Microano-structured CaWO _4/Bi _2WO _6 composite: Synthesis, characterization and photocatalytic properties for degradation of organic contaminants

摘要

The microano-structured CaWO _4/Bi _2WO _6 composite was successfully synthesized by a one-step hydrothermal route without using 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 spectroscopy (UV-vis DRS), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry-differential scanning calorimetry (TG-DSC) and Brunauer-Emmet-Teller (BET) theory. The results indicated that the composite has a two-phase composition: CaWO _4 and Bi _2WO _6. The photocatalytic activities of the CaWO _4/Bi _2WO _6 composite were evaluated for the degradation of Rhodamine B (RhB) dye and 4-nitrophenol (4-NP) in aqueous solution under visible-light irradiation (>420 nm), which were 4.5 times and 2.5 times higher than that of the pure Bi _2WO _6, respectively. On the basis of the calculated energy band positions, the mechanism of enhanced photocatalytic activity for the microano-structured CaWO _4/Bi _2WO _6 composite can be attributed to the effective separation of electron-hole pairs.