Preparation of WO3/TiO2/In2O3 composite structures and their enhanced photocatalytic activity under visible light irradiation

A novel visible light (lambda a parts per thousand yen 420 nm) active WO3/TiO2/In2O3 composite photocatalyst was prepared by a two-step process. At first, TiO2/In2O3 was synthesized utilizing maleic acid as an organic linker. Afterwards, WO3/TiO2/In2O3 composite heterojunction structure was prepared by the incipient wetness method. The composite was characterized by SEM mapping, high-resolution TEM, BET, UV-Vis diffuse reflectance spectroscopy, XPS and surface acidity measurement. The photocatalytic activity of the composite was evaluated through the decomposition of organic pollutants in gas and aqueous phases. The WO3/TiO2/In2O3 composite demonstrated greatly improved photocatalytic efficiency in compare with TiO2/In2O3 composite and Degussa P25 for the degradation of gaseous 2-propanol and evolution of CO2 and, 1,4-terephthalic acid in aqueous phase under visible light (lambda a parts per thousand yen 420 nm) irradiation. The concentration of WO3 in the composite was optimized to 3.5 mol% WO3/TiO2/In2O3. Based upon these observations, the mechanistic role of WO3 in enhancing the photocatalytic activity of WO3/TiO2/In2O3 has been suggested.