| Since the environment in the whole world deteriorates, using TiO2 photocatalysts to purify environment is emphasized. Current application is focused on the purification and the treatment of water and air. However, there exist many defects in the use of conventional powder photocatalysts, such as stirring during the process, segregating after the reaction and so on. TiO2 film photocatalysts can be used to overcome these defects and extend its industrial application. For example, TiO2 films photocatalysts can be used as antiseptic glazed tile, self-clean glass and so on. Present method used to prepare TiO2 films mostly includes sol-gel method. The films prepared by this method are uneven in thickness, which affects the optical quality of the films.In order to solve the films quality problem in traditional sol-gel method and to promote the use of TiO2 films as ecological building material, we did a series of research. In this paper, TiO2 films as ecological self-clean glass material prepared by magnetron sputtering method were discussed in the following aspects: the preparation technology of TiO2 films by magnetron sputtering method, the control of the surface microstructure, the effect of the surface microstructure on the photocatalytic activity and the optical performance of TiO2 films. SEM was used to observe the surface topography. XRD was used to explore the crystal form, and crystal size. XPS was used to research the valence and the composition of the films. UV-VIS was used to study the transmittance and the absorption threshold of the TiO2 films. In addition, the photocatalytic activity was evaluated by the means of following method: using UV light as light source and then observing the degradation process of methyl orange in water solution. The results are as follows:As the sputtering pressure increases, the atomic ratio of O to Ti increase in the films, which is attributed to the fact that the absolute oxygen content increases, as the pressure increases despite the ratio of 62 to Ar remains unchangless. At the same time, as the sputtering pressure increases, the films surface becomes rough and the degradation ability of the films on the methyl orange increases. While the sputtering pressure is great the films become rough, which results in larger surface area. The absorption ability of the film surface was increased, therefore, the photocatalytic activity if the thin film was enhanced. In addition, when the electron-cavity pairs migrates to the films surface, there is adequate water to react with these electron-cavity pairs in good time. This not only reduces the composition probability of the electron-cavity pairs but also produces a large number of highly activehydroxyls that enhances the photocatalytic ability.In the UV light region, the absorption dramatically increases that is caused by the absorption of the films substance, hi addition, as the heat treatment temperature increases the absorption threshold slightly occurs "red shift". From ambient to 500 when the heat treatment temperature increases, the crystallinity of the film increases, which enhances the degradation ability of the films on the methyl orange.Other conditions of magnetron sputtering method also affect the TiO2 films quality. During depositing, the matrix temperature increases, the crystal grain grows and the grain size increases. When the depositing time becomes very long, the equipment will probably be damaged, therefore, the depositing time was controlled in 25 minutes. The shorter the depositing time, the thinner the films, the lower the photocatalytic ability. As the sputtering power increases, the sputtering rate also increases. When the sputtering power is lower than 300 W the sputtering rate increases slowly; when the sputtering power is higher than 300 W the sputtering rate increases rapidly, so there exists a threshold. As the partial pressure of O2 increases the cathode voltage of the target increases in order to maintain the same current intensity and the sedimentation rate gradually decreases.
|
PDF Full Text Request