Structure and photocatalytic activity of bismuth tungstate nanoparticles synthesized by one-step solvothermal method

Abstract

Bi₂WO₆ has been synthesized by water, methanol or ethylene glycol assisted solvothermal method. The physical and photophysical properties of the as-prepared samples are characterized by XRD, UV-vis, SEM and BET surface area measurements. XRD results show orthorhombic Bi₂WO₆ with the average crystallite size of about 9.2 nm, obtained using ethylene glycol as the reaction solvent. By substituting ethylene glycol for deionized water or methanol as solvent, the size of Bi₂WO₆ increases. BET results indicate that the Bi₂WO₆ sample prepared in ethylene glycol has the largest surface area (56.5 m² g^–1). The photocatalytic activities of as-prepared samples have been evaluated by the degradation of methylene blue in an aqueous solution under visible light irradiation. The degradation ratio of MB over Bi₂WO₆ synthesized in ethylene glycol (97.1%) is much higher than that over Bi₂WO₆ synthesized in deionized water (82.8%) and methanol (50.0%) within 120 min. This may be attributed to its appropriate energy band structure, small crystallite size, and high surface area.