La-Ce-TiO_2纳米光催化剂的溶胶-微波法合成、谱学表征及其活性研究

以钛酸四丁酯为原料,采用溶胶-微波法(Sol-Microwave Method)合成了镧和铈共掺型纳米TiO2粉体(La-Ce-TiO2),借助XRD、XPS和UV-Vis等测试手段对其进行了表征,并以甲基橙为模型污染物考察了掺杂量对样品光催化活性的影响规律.XRD分析表明,所得粉体均为锐钛矿相纳米TiO2,且稀土元素镧和铈掺杂后纳米TiO2特征衍射峰宽化,强度降低;XPS分析表明,镧和铈掺杂后样品表面存在大量的氧缺位;UV-Vis吸收光谱表明,所得粉体在400 nm以下均有连续宽化的吸收带,且La和Ce掺杂后样品对光的吸收显著增强,这足由于La(Ⅲ)-O荷移跃迁以及Ce(Ⅳ)f→d跃迁和Ce(Ⅳ)-O荷移跃迁所致;光催化实验表明,La和Ce共掺杂能显著提高纳米TiO2的光催化活性,其中当La(Ⅲ)和Ce(Ⅳ)掺杂量分别为2%和0.04%时,纳米TiO2光催化剂具有较高的催化活性,自然光照射下光催化氧化处理卷烟厂蒸叶车间废水,效果较好,废水COD去除率达到86.11%.

La-Ce-Codoping Nano-Titania Photocatalyst:Preparation Via Microwave-Assisted Sol Process,Spectroscopy Characterization and Photocatalytic Activity

La-Ce codoping nano-TiO2 catalyst was prepared by microwave-assisted sol process with TBT and distilled water as forerunner body, ethanol as solvent and glacial acetic acid as inhibitor. The prepared samples were characterized by using XRD, XPS and UV-Vis techniques. Results of structural characterization indicated that the prepared samples were all pure anatase phase nano-TiO2 and their diffraction peak broadened obviously after La and Ce doping. Results of XPS analysis revealed that La—O bond existed in the samples and many oxygen vacancies were produced on the surface of TiO2 nanoparticles after La and Ce codoping. UV-Vis absorption spectra demonstrated that the prepared samples had strong and wide absorption band between 200 and 400 nm and the absorption intensity increased after La and Ce doping because of La(Ⅲ)—O charge-transfer transition, Ce(Ⅳ) f→d transition and Ce(Ⅳ)—O charge-transfer transition. Photocatalytic experiment results showed that the titanium dioxide’s photocatalytic activity increased obviously after La and Ce codoping. The optimal parameters for the preparation were obtained by adjusting the mole ratio of La and Ce in photocatalysts. When the doping amount of La and Ce was 2% and 0.04% respectively, the prepared sample exhibited high photocatalytic activity, the decoloration ratio of methyl orange solution was above 90%, and COD removal of cigarette factory wastewater was 86.11%.