镧在TiO_2薄膜中的非均匀掺杂对光催化性能的影响

Effects of La^(3+) Non-Uniformly Doping in TiO_2 Films on Photocatalytic Activities

采用溶胶-凝胶法制备了La3+非均匀掺杂的TiO2薄膜。通过对甲基橙的光催化降解实验来评价催化剂薄膜的催化活性,结果表明:La3+的掺杂方式对TiO2的催化活性有很大的影响,采用非均匀掺杂方式可以明显提高TiO2的催化活性,掺杂浓度以0.5%(原子分数)为最佳。紫外-可见漫反射光谱显示其吸收带边明显红移;电化学行为表明其光生空穴-电子对的形成能力和分离效率得到提高。通过比较太阳能光电池异质结的“窗口效应”理论,初步探讨了La3+非均匀掺杂对TiO2的光催化活性的影响机制。

TiO2 thin films non-uniformly doped by La^3＋ were prepared by sol-gel method. The comparison of thin film activities, which was characterized by photocatalytic degradation of methyl orange, shows that doping modes have great activities. The non-uniformly effects on photocatalytic doped TiO2 films result in good photocatalytic activities with an optimal concentration; about 0. 5% （atom fraction）. UV-Vis transmittance spectra indicate that the absorption edges of these TiO2 thin films shift to ward longer wave-lengths remarkably, and electrochemical behavior also reveales that e^--h^＋ pairs are prone to formation and separation under UV irradiation. The mechanism of photocatalytic activities are enhanced by La^3＋ non-uniformly doping was discussed on the analogy of the theory of “window effect” of solar cell heterojunction.