Synthesis, characterization and visible-light photocatalytic properties of Bi2WO6 and Bi2W2O9 obtained by co-precipitation method

The bismuth tungstates Bi2WO6 and Bi2W2O9 were prepared by co-precipitation method at different calcination temperatures. The oxides were characterized by different techniques such as simultaneous thermogravimetric and differential thermal analysis (TGA/DTA), X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), nitrogen physisorption, and scanning electron microscopy (SEM). The photocatalytic activity of such bismuth tungstates was evaluated by degradation of rhodamine B under visible light irradiation. The degradation of the dye followed a first-order reaction with k' = 5.6 x 10(-3) min(-1) and t(1/2) = 124 min for the best sample, which was Bi2W2O9 prepared at 700 degrees C. (C) 2010 Elsevier B.V. All rights reserved.