Preparation and Characterization of K6ZrW11O39Sn‐TiO2 Composite Catalyst for Solar Photocatalytic Degradation of Aqueous Dye Solutions

A novel photocatalyst, K(6)ZrW(11)O(39)Sn(.)12H(2)O (ZrW11Sn), was synthesized in our previous study. However, the utilization of ZrW11Sn was extremely limited because of its high solubility in water. A novel composite catalyst, ZrW11Sn-TiO2, was synthesized and characterized in this study. ZrW11Sn-TiO2 is of nanometer-scale and has a structure similar to that of anatase TiO2. The forbidden energy zone of ZrW11Sn-TiO2 is less than that of the synthesized pure TiO2, while its specific surface area is larger. The photocatalytic activities of ZrW11Sn-TiO2 were evaluated by its degradation of monoazo, disazo, anthraquinone, and three aryl methane dyes with solar irradiation in heterogeneous aqueous solutions. Results indicate that ZrW11Sn-TiO2 has higher photocatalytic activity than the synthesized pure TiO2, commercial anatase TiO2, H3PW12O40, and H4SiW12O40 doped TiO2. The optimum doping concentration of ZrW11Sn and the calcination temperature were 1.8wt % (ZrW11Sn) and 400 degrees C, respectively. ZrW11Sn-TiO2 showed a considerably high photocatalytic stability. When a Reactive Black 5 solution (200mL, 10mg/L; initial pH 6) with ZrW11Sn-TiO2 (0.2g/L) was irradiated for 60min with simulated sunlight, the decoloration rate was >98% even after four cycles. ZrW11Sn-TiO2 exhibited a better settling property than commercial TiO2, which made further separation treatment easier.