Preparation of Highly Ordered Cubic Mesoporous WO₃/TiO₂ Films and Their Photocatalytic Properties

Highly ordered cubic mesoporous WO 3 /TiO 2 thin films were prepared by spin coating via an evaporation-induced self-assembly (EISA) process, employing metal alkoxides as inorganic precursors and Pluronic F127 as a structure-directing agent. With the incorporation of WO 3 into TiO 2, the ordering of the mesopore structure has been appreciably improved. That is, the presence of 2−6 mol % WO 3 retards the crystallization to the anatase phase, and this leads to the relative stabilization of the mesopore structure. The characterization results suggest that the majority of incorporated W species are located at the surface of the mesopore wall instead of doping into the TiO 2 lattice. For the prepared cubic mesoporous WO 3 /TiO 2 thin films, the photocatalytic activity in decomposing 2-propanol in the gas phase was optimized at 4 mol % of WO 3 concentration. Its photocatalytic activity was 2.2 times that of a mesoporous TiO 2 film and 6.1 times that of a nonporous TiO 2 film derived from a typical sol−gel method. The enhanced photocatalytic activity of WO 3 /TiO 2 is ascribed to the increase in surface acidity.