Pt对TiO_2薄膜的结构及可见光光催化活性的影响

The effect of Pt on the microstructure and photocatalytic properties of TiO_2 system under visible illumination

采用溶胶-凝胶法辅之以离子溅射制备了TiO2／Pt／TiO2纳米多层薄膜和TiO2／TiO2薄膜。通过SEM观察表明，TiO2／Pt／TiO2中二氧化钛颗粒的平均尺寸在20～40nm之间，而TiO2／TiO2中颗粒平均尺寸在40～80nm之间。TiO2／Vt／TiO2纳米多层薄膜的总厚度约为160nm。TEM观察及SADP结果证实单质Pt颗粒尺寸在20～40nm之间，二氧化钛为锐钛矿型。与TiO2／TiO2薄膜相比，TiO2／Pt／TiO。的光吸收曲线红移了30nm，与此同时，除本征吸收边（365nm）外，它在可见光波段还出现了一个新的吸收边650nm，对应的带隙为1．9leV，这种现象归因于沉积Pt后TiO2／Pt／TiO2薄膜中存在金属与基体的界面强相互作用（SMSI）。在可见光光降解甲基蓝的实验中，扣除甲基蓝自身的分解，TiO2／Pt／TiO2多层纳米复合薄膜2h后的光降解率为18．1％。

TiO2/Pt/TiO2 composite film was obtained by sol-gel method together with sputtering and pure TiO2 film also prepared using the same sol. SEM results show that the average particle size was among 20-40nm in TiO2/Pt/TiO2 ,while it was among 40-80nm in TiO2/TiO2. The cross-section SEM results show that the whole thickness was 160nm. The TEM and electron diffraction analysis show that the deposited Pt aggregates into 20- 40nm granules. The TiO2 is in the form of anatase phase after heat treatment. Compared with TiO2/TiO2 film, the absorbance curve of TiO2/Pt/TiO2 composite film has red-shifted by 30nm. Further more,it exhibits a new ahsorbanee edge at 650nm,corresponding to a band gap of 1.91eV,other than its characteristic absorbance edge 365nm,which was ascribed to the strong metal-support interaction effect （SMSI）. Experiments of photobleaching methyl blue show that the TiO2/Pt/TiO2 film exhibits a significant photocatalytic activity of 18.1% under visible light illumination when the decomposition of methyl blue is deducted.