Preparation And Photocatalystic Properties Of TiO₂ Nanopowders And TiO₂ Composite Films

Titania (Ti02), which can decompose most organic pollutants into inorganic substances under UV irradiation, has become a hot research area because of its attractive application in the treatment of environmental pollutants. In this paper, anatase Ti02 powder with the average crystallite size of 21.2 nm was prepared by high temperature thermo-hydrolysis method at 220 0C, which showed high photocatalystic activity in photocatalytic degradation of safranine. The degradation ratio of safranine reached 98.5 % after 75 minutes UV irradiation. Since the fixed catalysts are more practicable to the treatment of pollutants than the powder catalysts, we prepared Ti02 films supported on the porous titanium plates by sol-gel method. The photocatalytic activity of Ti02 films was investigated by the photocatalytiv degradation of methyl orange. The results showed that Ti02 films were anatase and the average crystallite size of Ti02 was 20 nm. The film with three-time doping showed the best photocatalytic activity. To obtain better photocatalysts, ZnO-Ti02 and W03-Ti02 composite film photocatalysts were prepared by sol-gel method on porous titanium plates. It was found that the ZnQ-Ti02 film photocatalyst calcined at 450 0C for lh with 0.1 molar percent of ZnO showed higher photocatalytic activity than that?of pure Ti02 film by 77.0%, while the 0.5 mol% W03-doped Ti02 film by 96.7 %. Ti02 supported on the porous titanium plates consists of both the anatase phase and the rutile phase, indicating that the addition of appropriate ZnO and W03 could effectively decrease the temperature of phase from anatase to rutile.