Effect of pH Values on Photocatalytic Properties of Bi_2WO_6 Synthesized by Hydrothermal Method

摘要

Highly crystalline orthorhombic Bi2WO6 powders were hydrothermally synthesized from aqueous solutions of Na2WO4·2H2O and Bi (NO3)3·5H2O over a wide range of pH. The effect of pH on morphologies, sizes and properties of the Bi2WO6 crystals was investigated. The band gaps of the as-prepared Bi2WO6 were determined from the onset of the absorption edge of UV-vis diffuse reflectance spectra. The methyl orange photodegradation was employed as a probe reaction to test the photocatalytic activity of the as-prepared samples under visible light irradiation. The photocatalytic activities of methyl orange degradation under visible light irradiation are strongly dependent on the pH used in the synthesis. The highest efficiency is observed at pH=7.