钕掺杂提高TiO_2光催化活性的机制

Enhancement of Photo-Catalytic Properties and Activity of Nd^(3+)-Doped TiO_2 Powders

采用X射线衍射(XRD),BET吸附,X射线光电子能谱(XPS)表征了溶胶凝胶法制备的Nd掺杂TiO2光催化剂的晶体结构、表面电子结构与化学组成。以甲基橙为有机底物,测试Nd掺杂对光催化剂吸附性能和光催化活性的影响。结果表明,Nd掺杂可阻碍TiO2的晶相转变,减小光催化剂的晶粒尺寸,比表面积增大。Nd掺杂提高光催化剂表面三价钛(TiⅢ)的含量及其对甲基橙的吸附能力是其提高TiO2光催化降解甲基橙活性的主要原因。Nd掺杂量为1.2%时,光催化剂活性最高。

The crystal pattern and parameter, the specific area, the surface chemical state of pure TiO_2 and Nd^(3+)-doped TiO_2 powders prepared by the sol-gel method were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and BET method respectively. The methyl orange (MO) was chosen to be the probe compound to measure their adsorptive properties and photo-catalytic activity. The results shows that the Nd doping hinders the crystal transformation and decreases the relative intensity of (101) peak. The crystallite sizes of Nd^(3+)-doped TiO_2 powders decrease while their specific surface area increase owing to the Nd doping. The XPS measurement show that the surface chemical state can be improved and the content of Ti(Ⅲ) on their surfaces increases with the Nd doping. The relationship between the physicochemical properties and the photo-catalytic activity of the photocatalysts was discussed. The enhancement of photo-catalytic activity of Nd^(3+)-doped TiO_2 powders increase because of their adsorption capacity and the suitable percent of Ti(Ⅲ) on the surface. The adsorption and photo-degradation experiments show that the optimum molar content of Nd may be 1.2%.