Modification Of Titanium Dioxide Photocatalyst

In recent years, titanium dioxide (TiO₂) has been a popular photocatalyst for the treatment of organic pollutants in water and air. However, TiO₂ photocatalysts have an inherent and significant drawback; that is, the photogenerated charge carriers (hole-electron pairs) can recombine. Therefore, to increase the photocatalytic activity of TiO₂, it is important to decrease the recombination of photogenerated charge carriers. Coupling TiO₂ with other semiconductors can provide a beneficial solution for this drawback. TiO₂ and SnO2 are rutile crystal, but have different property. The energy gaps of these two semi-conductors are match, which can prevent the recombination of photogenerated charge carriers,and show efficient photoactivity.This dissertation consists of following contents.1. The sol-gel technique has been used to prepare SnxTi1-xO2 composite oxide with different amounts of Sn. X-ray diffraction (XRD), was used to characterize the phase transition at different heat treatment temperature. In some way, Sn doping promote the phase transition from anatase phase to rutile phase and the grain size of the SnxTi1-xO2 composite is smaller than that of TiO₂.2. The photo-catalyst tests was evaluated by decomposition of methylene blue and neutral red solution. As a result, the SnxTi1-xO2 composite oxides show a more efficient photoactivity for degradation of methylene blue and neutral red in solution, and the photo-catalyst activity is different when x is different in the SnxTi1-xO2.3. Sol - gel method was prepared by Sn-Li-F co-doped photocatalyst of TiO₂. Using the degradation of methylene blue photo-catalyst in aqueous solution, it was found that photocatalytic degradation of methylene blue solution with the light absorbance time index similar to obey the law. By comparing the solution of methylene blue light of life to evaluate the photocatalytic efficiency of the catalyst. Sn-doped single time, optimize the molar ratio of 5% of doping and heat treatment temperature of 600℃. At times on this foundation to further the formation of LiF 3%-doped Sn-Li-F ternary 近年来,TiO₂作为一种用途很广的半导体材料,因其活性高,稳定性好,对人体无毒,成本低且在光催化处理污染水和空气中已广泛应用,而成为最具潜力的光催化剂。然而TiO₂本身有其固有的缺陷,光生电子-空穴对容易复合,这降低了其光催化活性。因此,要提高TiO₂的光催化活性,就应减少光生电子与空穴的复合。其中将TiO₂与其它氧化物半导体复合可能是提高其光催化活性途径之一。TiO₂å’ŒSnO2都是有金红石型的晶体结构,但是性质差别很大,这两种半导体材料能级匹配,光生电子和空穴可以发生有效的分离,使它们复合几率减小,从而可以提高TiO₂的光催化活性。本文主要研究内容如下:1.利用溶胶-凝胶法合成了SnxTi1-xO2复合氧化物,考察了不同退火温度和不同的锡含量对材料晶型的影响。采用x-射线衍射(XRD)对合成材料进行了分析表征。结果表明,SnxTi1-xO2复合氧化物中锡促进了二氧化钛中锐钛矿相向金红石相的转变,但锡的加入能抑制材料颗粒的生长,TEM表征说明SnxTi1-xO2复合氧化物的粒径比纯TiO₂的粒径要小。2.利用亚甲基蓝这种偶氮染料水溶液对合成的材料进行了光催化活性测试,测试结构表明,SnxTi1-xO2复合氧化物的光催化活性比纯TiO₂的光催化活性要好,并且SnxTi1-xO2复合氧化物中锡掺杂量不同其催化活性也不同,单一掺杂Snæ—¶,优化出5%的摩尔比掺杂量和600℃的热处理温度。3.溶胶-凝胶法制备了Sn-Li-F共掺杂的TiO₂光催化剂。采用该催化剂光助降解亚甲蓝水溶液时,发现光催化降解亚甲基蓝溶液的吸光度随光照时间的变化近似服从指数规律。通过比较亚甲基蓝溶液的光照寿命以评价催化剂的光催化效率。在单一掺杂Sn基础上进一步掺杂LiF 3%形成Sn-Li-F三元共掺杂的TiO₂光催化剂,经500℃热处理后,光降解亚甲蓝的效率又有提高。...