La掺杂对TiO_2薄膜性能的影响

The influence of La-doping on the properties of TiO_2 thin films

用溶胶-凝胶法制备TiO_2以及La掺杂TiO_2的前驱体凝胶,将其均匀旋涂不同层数制备出不同厚度的薄膜,研究了La掺杂对TiO_2薄膜结晶性能、表面形貌、光学特性和亲水性能的影响.结果表明:在500℃可以获得结晶性良好的锐钛矿相TiO_2薄膜;随着La掺杂量的增加,薄膜中TiO_2晶粒会变大,同时引起紫外可见光谱中吸收边的蓝移.掺La的TiO_2薄膜经紫外照射后其接触角明显高于未掺杂样品,主要原因是到达表面的活性载流子相对减少.一方面,大的TiO_2晶粒使得光生载流子到达光催化表面的路程变长,电子-空穴对的复合几率也随之变大;另一方面,未完全替代Ti的La可能成为光生电子-空穴对的复合中心.因此,通过La的掺杂可以有效调节TiO_2晶粒尺寸和光致接触角.

Anatase TiO2 and La-doped TiO2 thin films have been prepared by using sol-gol method and post-annealing at 500 ℃. The crystal structure, morphology and photocatalytic activity were investigated using X-ray diffraction （XRD）, atomic force microscope （AFM）, UV-VIS spectrophotometer and contact angle meters. The results showed that the doping of La could improve the crystallization of TiO2, and increase the band gap of TiO2 film. However, the La will act as the recombination center of electron-hole, resulting in the increase of the contact angle of TiO2 films.