【作者】 李建通；

【导师】 杨娟； 缪娟；

【作者基本信息】 河南理工大学 ， 应用化学， 2010， 硕士

【摘要】 本课题通过采用金属离子掺杂技术,旨在制备出具有可见光响应的新型TiO₂光催化剂,使其光响应波长红移至可见光区,能更大程度地利用可见光降解有机污染物。具体进行了以下几个方面的研究:（1）铋掺杂改性TiO₂纳米粒子的制备及其可见光光催化性能研究;（2）铈掺杂改性TiO₂纳米粒子的制备及其可见光光催化性能研究;（3）镨掺杂改性TiO₂纳米粒子的制备及其可见光光催化性能研究;（4）钕掺杂改性TiO₂纳米粒子的制备及其可见光光催化性能研究。通过XRD、XPS、FT-IR、UV-Vis、TEM、BET以及荧光光谱等手段对样品的结构、形貌、组成以及光谱特性进行了表征,研究结果如下:1. TiO₂经铋掺杂改性后,晶型以锐钛矿为主,晶粒粒径较纯TiO₂小,说明掺杂铋离子有效抑制了纳米晶体的转化及生长。掺杂后催化剂的吸收光谱发生了红移,光生电荷复合率降低。可见光照射下降解罗丹明B的实验显示,Bi掺杂的TiO₂具有较高的稳定的催化活性,其中掺杂量为2.0 %（mol %）时光催化效率最佳。在光催化降解过程中,催化剂表面吸附的·OH对罗丹明B的降解起着最重要的作用。2.经铈掺杂的TiO₂,其可见光催化活性明显得以提高,并且稳定性较好。在光催化降解过程中,催化剂表面吸附的·OH对罗丹明B的降解起着最重要的作用。其最佳掺杂量为3.0 %（mol %）,溶胶-水热法合成的Ce-TiO₂的晶型以锐钛矿为主,掺铈后晶粒粒径变小,表明Ce掺杂有效抑制了纳米晶体的生长。紫外可见吸收光谱表明,Ce的掺杂使TiO₂的吸收光谱发生显著红移。荧光光谱分析结果表明Ce掺杂可有效降低光生电荷的复合几率。3.镨掺杂TiO₂光催化剂具有良好的稳定性,晶型以锐钛矿为主,且晶粒粒径比未掺杂的要小,说明Pr掺杂有效抑制了纳米晶体的生长。光催化降解实验表明,掺杂量为2.0 %（mol %）时,样品的光催化活性最佳。Pr掺杂后,TiO₂表面吸附的H2O和羟基的数量有所增加,益于TiO₂光催化剂活性的提高。荧光光谱表明,2.0 % Pr-TiO₂的表面捕获态比纯TiO₂低,并能够抑制光生电荷的复合,从而提高TiO₂的光催化活性。在光催化降解过程中,催化剂表面吸附的·OH对罗丹明B的降解起着最重要的作用。4.经钕元素掺杂改性的TiO₂光催化剂,具有良好的稳定性。当Nd:Ti=3.0:100 （mol %）时,其光催化活性最佳。Nd-TiO₂的晶型以锐钛矿为主,且其晶粒粒径比未掺杂的粒径小。低温N2吸附-脱附测试结果表明,Nd的掺杂使得TiO₂粉体比表面积增大,孔体积也随掺杂量的增大而增大。红外吸收图谱显示,Nd掺杂后的TiO₂表面的H2O和羟基的数量有所增加,利于TiO₂光催化剂活性的提高。另外,实验表明,在光催化过程中产生的O2·-和·OH都是对有机物的降解起重要作用的活性氧物种,而催化剂表面吸附的·OH是光催化反应过程中最重要的活性氧物种。更多还原

【Abstract】 New TiO₂ photocatalysts of visible response were prepared by metal ions doping in order to extend its range of photo-response spectrum and increase its photocatalytic activity. The present studies include the following aspects: （1） the preparation of Bi-doped TiO₂ and its photocatalytic performance under visible light illumination; （2） the preparation of Ce doped TiO₂ and its visible light photocatalytic property; （3） the preparation of Pr-doped TiO₂ and its photocatalytic performance under visible light illumination; （4） the preparation of Nd doped TiO₂ and its visible light photocatalytic property.1. The Bi doped TiO₂ is mainly anatase and its grain size is smaller than pure TiO₂, which indicate that doping effectively suppresses the phase transformation and growth of nanocrystals. UV-vis DRS show an extension of light absorption into the visible region. Fluorescence spectra indicate the recombination rate of photo-generated charge decreases. The results of the degradation of Rhodamine B under visible light irradiation show that Bi-doped TiO₂ has a high and stable photocatalytic activity, when the optimal doping concentration is 2.0 % （mol %）. In the photocatalytic degradation process, the·OH which adsorbed on the surface of TiO₂ plays the most important role.2. The Ce-doped TiO₂ （Ce-TiO₂） has good durability and enhanced visible light photocatalytic activity. In the photocatalytic degradation process, the adsorbed·OH of Ce-modified TiO₂ plays the crucial role. The results of the degradation of Rhodamine B in the visible experiments show that the optimum doping amount is 3.0 % （mol %）. The Ce-TiO₂ consists mainly of anatase and the grain size is smaller than that of pure TiO₂, suggesting that doping Ce effectively inhibits the growth of nanocrystals. UV-visible absorption spectra show that Ce doping lead to the red shift of absorption spectra. Fluorescence spectra show lower recombination rate of the photogenerated charge by Ce doping.3. Pr-doped TiO₂ （Pr-TiO₂） has good durability and the main crystal anatase, and its grain size is smaller than pure TiO₂, indicating that Pr doping effectively inhibits the growth of nanocrystals. The optimal doping amount is 2.0 % （mol %）. The increasing of the amount of the adsorbed H2O and hydroxyl groups which showed by FT-IR improves the photocatalytic activity of Pr-TiO₂. Fluorescence spectra show that the surface state of 2.0 % Pr-TiO₂ is lower than that of pure TiO₂, which suggests that photo-charge recombination rate decreases. These results cause the enhanced photocatalytic property of Pr-TiO₂. Furthermore, the·OH which adsorbed on the surface of TiO₂ plays the most important role on the degradation of RhB.4. Nd-doped TiO₂ （Nd-TiO₂） has good durability. When the Nd: Ti = 3.0:100 （mol %）, the photocatalyst shows the highest activity among the samples of different contents. The Nd-TiO₂ consists mainly of anatase and the grain size is smaller than that of pure TiO₂, suggesting that doping Nd effectively inhibits the growth of nanocrystals. Compared with pure TiO₂, the results of BET analysis demonstrate by Nd doping the surface area powder and pore volume of Nd-TiO₂ significantly increase. According to FT-IR, the amount of the surface-adsorbed H2O and hydroxyl groups increase, which improves the activity of photocatalyst. In addition, the experiments show that the reactive oxygen species of O2? - and ?OH generated in the photocatalytic process play significant roles. Whereas, the·OH adsorbed on the surface of TiO₂ plays the most important role on the photocatalytic degradation of dye RhB under visible light illumination.更多还原