采用溶胶-凝胶法合成了TiO2溶胶和SnO2溶胶, 使用浸渍提拉法在低温下制备出底层为金红石型SnO2, 表层为锐钛矿型TiO2的复合膜. 考察了不同SnO2薄膜层数对TiO2/SnO2复合膜光催化活性的影响, 并对其光催化活性提高的机理
进行了探讨. 结果表明, SnO2层的加入能有效提高TiO2薄膜的光催化活性, 随着SnO2薄膜层数的增加, 光催化活性先增大后减小, 但始终高于单一的TiO2薄膜. 这是由于SnO2的导带电位低于TiO2的导带电位, SnO2的价带电位高于TiO2的价带电位, 紫外光照下, TiO2中产生的光生电子注入到SnO2层, SnO2中空穴注入到TiO2层, 有效抑制了薄膜内电子-空穴对的复合, 增加了复合薄膜表面空穴的浓度, 因而光催化活性得到了显著的提高.
TiO2/SnO2 composite films were prepared on a slide glass with a sol-gel method at low temperature. The influence of different dip-coating times of SnO2 layers on the photocatalytic activity of TiO2/SnO2 composite films was investigated. In addition, the mechanism of the photocatalytic activity enhancement of TiO2/SnO2
composite film was also analyzed. The results show that the photocatalytic efficiency of TiO2 film is enhanced by using SnO2 layer as a substrate. Since the conduction band (CB) of SnO2 is lower than that of TiO2, and the valence band(VB) of SnO2 is higher than that of TiO2, electrons transfer from TiO2 to SnO2, while holes oppositely diffuse into the SnO2 layer . Thus, the charge recombination is suppressed more efficiently, and more holes can reach the TiO2 surface to cause oxidation
reaction. This is believed to be the main reason for the photocatalytic activity enhancement of the TiO2 film photocatalyst.
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