Hydrothermal synthesis, characterization and photocatalytic activities of Bi2MoxW1-xO6 solid solution

Bi2MoxW1-x(x=0-1) solid solutions were successfully synthesized via a facile hydrothermal method. The obtained products were characterized by X-ray diffraction, UV-Vis diffuse reflectance spectra and FT-IR spectrum. With an increase of Mo content, XRD patterns of the as-synthesized products show that the peaks at 2 theta=33 degrees, 47 degrees, 56 degrees gradually split, and the value of I(131)/I(200) gradually increases and then slowly decreases. FT-IR absorb band around 821 cm(-1), which refered to the vibration frequency of the metal-oxygen band, is monotonically shifted to 842 cm(-1). According to DRS calculations, the band gap of the samples are 2.75, 2.55, 2.50, 2.45, 2.59 and 2.63 eV when x is 0, 0.25, 0.5, 0.75, 0.9 and 1, respectively. This result demonstrates the formation of soluble solid solution. The photocatalytic activities of the products were evaluated by monitoring the degradation of RhB under visible light. It is found that, among solid solutions, the Bi2Mo0.75W0.25O6 exhibites the highest photocatalytic activity which mainly attributes to the special structure of solid solution and the lower energy band gap.