Preparation of transparent particulate MoO3/TiO2 and WO3/TiO2 films and their photocatalytic properties

By monolayer coverage of highly acidic semiconductors, such as MoO3 and WO3 on the surface of TiO2 nanoparticles (Degussa P25), the stability of colloidal suspensions in aqueous solution can be greatly improved. The average diameter of agglomerated MoO3/TiO2 and WO3/TiO2 particles in aqueous suspension is only 85-110 nm, respectively, which is about one-fifth to one-fourth of that of pure TiO2 suspension. The optically transparent photocatalytic films have been prepared with deposition of these colloidal suspensions. The colloidal particles in aqueous solution and the prepared transparent photocatalytic films were characterized with TEM, SEM, AFM, and other spectroscopic techniques. It has also been found that the photocatalytic activity of WO3/TiO2 film is 2.8-3 times that of pure TiO2 film in decomposing gas-phase 2-propanol, while MoO3/TiO2 film is less effective.