Ag/TiO2薄膜结构和光催化性能研究

采用溶胶-凝胶技术制备了Ag掺杂的TiO2薄膜.用XRD、氮吸附法、UV-VIS-NIR分光光度计以及XPS对Ag掺杂后TiO2薄膜结构的变化进行了分析;用分光光学法通过在紫外光照下分解亚甲基蓝的实验比较了TiO2薄膜与Ag/TiO2薄膜的光催化性能.结果发现,掺杂适量的Ag有助于TiO2薄膜光催化氧化性能的提高,原因在于:（1）Ag通过引入耗尽层提高了TiO2的电荷分离能力,并吸引空穴向薄膜表面移动,结果使薄膜表面空穴的浓度提高,薄膜光催化效率提高;（2）Ag减小了TiO2粒子的粒径,使TiO2禁带宽度增大,薄膜光催化氧化的能力提高;（3）Ag掺杂后,TiO2薄膜表面对-OH基和水的吸附增加,使光照后TiO2薄膜表面活性自由基·OH的浓度增加,空穴向薄膜所吸附物质的转移能力提高.

Structure and Photocatalytic Activities of Ag/TiO2 Thin Films

Nanometric TiO2 thin films doped with Ag were prepared by the sol-gel method. The effects of Ag on the structure of TiO2 films were systematically studied by means of X-ray diffraction, BET nitrogen adsorption, UV-VIS-NIR transmission spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic activity of Ag/TiO2 thin films was characterized and studied in photocatalytic degradation of methylene blue under UV irradiation in comparison with pure TiO2 thin films. The results showed that suitable amount of Ag effectively improved photocatalytic activity of TiO2 thin films. The mechanism could be ascribed to that: (1) The electron-hole pair separation efficiency of TiO2 films was improved by the introduction of Ag. The concentration of photoholes at the surface of TiO2 films increased; (2) TiO2 particle sizes decreased while Ag wasintroduced, which further widened the band-gap of TiO2 and improved its photocatalytic redox capability; (3) The absorption of -OH and H2O on TiO2 films was increased, which improved the photoholes transfer efficiency and the concentration of reactive -OH group on TiO2 thin films after UV irradiation.