负载型TiO₂光催化剂的制备及性能研究

【作者】 王慧；

【导师】 宋洪昌；

【作者基本信息】 南京理工大学 ， 材料学， 2006， 硕士

【副题名】纳米TiO_2/电气石复合光催化剂的制备及性能研究

【摘要】 以微米级电气石为载体，采用溶胶—凝胶法制备了纳米TiO₂／电气石复合光催化剂，通过光催化降解甲基橙实验考察复合光催化剂的活性。研究表明：制备复合颗粒的最佳工艺条件为钛酸丁酯：无水乙醇：水：二乙醇胺=1：30：1：1（摩尔比），水解温度为40℃；焙烧温度为550℃；负载3次。SEM显示纳米TiO₂球形粒子先形成微粒簇，再均匀包覆在电气石表面形成颗粒膜层；TiO₂粒子的平均粒径为18nm；复合光催化剂对甲基橙溶液的降解率为60.2％，明显优于纯TiO₂（40.9％）。对电气石提高TiO₂光催化效率的机理进行分析，电气石的表面电场有利于抑制光生电子—空穴对的重新复合，从而提高光量子效率。 为了进一步提高复合光催化剂的催化效率，在纳米TiO₂／电气石复合光催化剂制备过程中添加聚乙二醇（PEG），增加颗粒膜层的比表面积，或掺杂稀土元素改性。实验表明：添加20％（摩尔含量）的PEG-600，甲基橙的降解率从60.2％提高到85.1％；掺杂1％（质量含量，下同）的Y元素，甲基橙的催化降解率提高到88.4％，掺杂0.8％的La元素，降解率为93.6％。对PEG（或稀土元素）与电气石共同提高TiO₂光催化作用的机理进行了初步分析。更多还原

【Abstract】 Titanium dioxide coated tourmaline composite photocatalysts were prepared via sol-gel method, and their photocatalytic activity were evaluated by probe reaction of methyl orange degradation. The optimal preparation conditions of composite photocatalysts are as follows: the molar ratio of tetrabutyl titanate, ethanol absolute, distilled water and diethanolamine equal to 1:30:1:1, hydrolysis reaction at 40℃, calcination at 550℃, and the three times coating of TiO₂ films. The SEM photos show that the clusters of TiO₂ nanocrystallite form on the surface of fine tourmaline particles, and the average crystallite size of TiO₂ is about 18nm. The photocatalytic results show that the decoloring ratio of methyl orange on the surface of the composite photocatalysts is 60.2%, much higher than that on the surface of pure TiO₂ （40.9%）. The possible interaction mechanism of tourmaline is disscused, i.e. the surface electric field of tourmaline can capture the photogenerated electrons, preventing the combination of the photogenerated electron-hole pairs and leading to an increase in efficiency of photo-degradation.The improvement on titanium dioxide coated tourmaline composite photocatalysts were made using polythylene geycol （PEG） as an additive and rare earth ions as dopants. The results show that both the methods markedly enhanced the photocatalytic activity of the composite photocatalysts. The decoloring ratio of methyl orange was enhanced from 60.2% to 85.1% when adding 20%（in molar ratio） PEG-600, 88.4% when doping l%（in mass） Y₂O₃, 93.6% when doping 0.8%（in mass） La₂O₃. Their possible mechanism were preliminarily investigated in this paper.更多还原