Preparation And Heat Treatment Of TiO₂/SrTiO₃Composite Film And Its Photocatalytic Properties Research

As a kind of light catalyst SrTiO3is used to water purifiction, but its application is shortened according to high-enegy band gap. TiO2has the same band gap as SrTiO3in enegy, while the conduction band and valence band level are different. In order to improve the efficiency of photocatalytic, composite photocatalyst of T1O2and SrTiO3came to exist.In this paper, photocatalytic TiO2film, SrTiO3film and TiO2/SrTiO3composite film were prepared by sol-gel spin coating. First using scanning electron microscope (sem), X-ray diffraction analysis of samples, studied the TiO2/SrTiO3heterojunction film structure light catalytic performance; Then the heat treatment process on the photocatalytic activity of TiO2/SrTiO3composite film; Further TiO2/SrTiO3composite film was studied in different conditions (such as PH value, initial concentration of methylene blue, etc.) the change of photocatalytic performance. The results show that:1. The photocatalytic performance of SrTiO3thin film with different layers was studied and determined that the best photocatalytic film coating layer number was5. The photocatalytic degradation rate of TiO3/SrTiO3composite film was increased44.5%than TiO2thin film, and57.1%than SrTiO3thin film, which showed that the combination of TiO2and SrTiO3has higher photocatalytic activity. Micro-porosity holes with tiny cracks and potholes was detected on TiO2/SrTiO3composite film, which was proved useful to light catalytic degradation reaction. Four different TiO2/SrTiO3films were studied,"one layer TiO2film+four layers SrTiO3film" structure has the highest photocatalytic degradation rate,which eliminated72.1%methylene blue in water in2hours.2. The optimum annealing temperature of pure TiO2thin film is about500℃, too low or too high temperature would reduce the photocatalytic ability. For the TiO2SrTiO3composite film, TiO2annealing between450-850℃,2h for the degradation of methylene blue rate is around60%, shows that TiO2annealing temperature on the photocatalytic degradation rate of TiO2/SrTiO3composite film of the impact is not big. TiO2holding time falls below60min, photocatalytic degradation rate is slightly lower than60%, TiO2holding time after more than60min, photocatalytic degradation rate of slightly more than60%, and with the extension of heat preservation time photocatalytic degradation rate is no longer increasing. The eliminated ratio of methylene blue was higher5.6%for2hour, if the TiO2was air cooled while preparing TiO2/SrTiO3composite film.3. The degradation rate with methylene blue was decreased when the TiO2/SrTiO3was repeatly used. The beforehand adsorption time has little influence on the degradation rate of TiO2/SrTiO3composite film, the maximum degradation rate was only1.9%higher than the minimum degradation rate in2hours beforehand adsorption. The photocatalytic activity of TiO2/SrTiO3composite film were similar in weak acid solution, weak base solution and neutral solution environment. The photocatalytic activity of TiO2/SrTiO3composite film is reduced in strong acid solution, while increased in strong base solution. With the initial concentration of the solution increasing, the photocatalytic degradation rate of TiO2/SrTiO3composite film was slowly decreased. The In (Co/Ct)-t curve showed a good linear relationship, and the reaction was the first order reaction kinetics equation, when in the low solution concentration. The Ct-t curve showed a good linear relationship, and the reaction was the zero order reaction kinetics equation, when in the higher solution concentration, and the excessive concentration was8mg/L-12mg/L.