Study On Preparation And Photocatalystic Properties Of ZnO-TiO₂ Composite Film

At present, film photocatalytic is studied mostly for treating with water pollution. Because the film will not bring the secondary pollution, and can be used again. ZnO film and TiO₂ film is mostly used as photocatalyzer, but they have some disadvantage, as they can only absorb little of the sun-light energy, the photoluminescence exciton compounds mostly, and they can be eroded easily by light. Complex semiconductor film is a good method to ravel out these problems. We advanced a new method to produce complex semiconductor film, mix sol method.We studied the process of making ZnO film and TiO₂ film, also studied the new process of making ZnO-TiO₂ film with mix sol method. We had made out ZnO film, TiO₂ film and ZnO-TiO₂ film with better exterior configuration and performance. We studied the viscosity change of sol with the old time by revolving viscometer, the light absorption performance of thin film by uv-visible light photometer, the photocatalytic performance of ZnO-TiO₂ film by photocatalytic degradation of methyl orange. We also compared the photocatalytic performance of complex film making in different method.We confirmed the new process of making ZnO-TiO₂ film by studing the orde of mixing sol, the proportion of mixing sol, the speed of drawing film, the layers number of film, and the process of heat treatment. The new process as follows: first, let the ZnO sol and TiO₂ sol to old 24 hour respectively, then put the ZnO sol into the TiO₂ sol slowly under stirring with magnetic whisk, keep stirring for half hour, let the mix sol to old for 24 hour at nature condition. Dip the clean glass into the mix sol for about 30 seconds, then drawing at the speed of 10 mm/s for 8 layers, the dryness process of each layer is as same as the ZnO film. Put the dry film into the stove, Let the stove temperature to rise to 550℃at the speed of 3℃/min, keep the temperature for 2 hour.We found the light absorption band border of the ZnO-TiO2 film made by mixing sol can be moved to 500 nm around, the photocatalytic degradation rate of methyl orange can rise to 90%, so the complex film made by mixing sol is better in either light absorpiong or photocatalytic.