【作者】 解晓青；

【导师】 尚庆坤；

【作者基本信息】 东北师范大学 ， 分析化学， 2010， 硕士

【摘要】 本文通过稀土离子Tm3+、Yb3+掺杂和窄带半导体CdS(Eg=2.5eV)的复合,对纳米TiO2进行了改性研究,制备出新型Tm3+-Yb3+ /TiO2/ CdS纳米复合催化剂。稀土离子的上转换发光作用,可以将低能的可见光转化为高能的紫外光,CdS的窄禁带宽度,可以扩展纳米材料的光谱吸收范围,这两种改性方法都能够抑制光生电子和空穴的复合,从而提高二氧化钛纳米复合催化剂的光催化降解效率。主要研究内容如下:1.采用溶胶-凝胶法合成了新型稀土离子Tm3+-Yb3+共掺杂的纳米TiO2/CdS复合光催化剂,运用紫外-可见漫反射光谱、X射线衍射、透射电镜和X射线光电子能谱等分析手段对催化剂体相及表面结构进行了详细表征。2.以三基色灯为光源,利用Tm3+-Yb3+/TiO2/CdS纳米复合催化剂,进行了光催化降解甲基紫、苯酚的实验研究,考察了光催化剂加入量、甲基紫或苯酚溶液初始浓度、光照时间及pH条件等对降解率的影响。结果表明,催化剂加入量为1.5g/L,甲基紫溶液浓度为20mg/L,并且在pH=2的条件下光照2h后,甲基紫的降解率达到98.13%。当催化剂加入量为4g/L时,光照12h后,苯酚的降解率达到73.52%,添加微量H2O2,光照12h后,苯酚降解率达到88.73%。3.对甲基紫和苯酚光催化降解过程的动力学特征进行了研究,并结合复合光催化剂的各种光学特性,讨论了光催化反应过程中的能量转移机理。更多还原

【Abstract】 Doping the rare-earth ion Tm3+, Yb3+ and compounding the narrow-band semiconductor CdS (Eg=2.5eV) with TiO2 seem to be an effective method. The upconversion luminescence effect of the rare earth ion can produce a higher excitation light. Compounding with the narrowband of CdS can expand the range of the absorption. Both modified methods not only inhibit the recombination of photo-generated electrons and holes, but also improve the photodegradation efficiency.1. A new Tm3+-Yb3+/TiO2/CdS nano-composite photocatalyst have been synthesized by a sol-gel method. UV-Vis diffuse reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the optical properties, structure and composition of samples.2. The photocatalytic degradation methyl violet and phenol were investigated in Tm3+-Yb3+/TiO2/CdS aqueous suspensions under the three-color light irradiation. The effects of the catalyst dosage, initial concentration of methyl violet or phenol, irradiation time and pH wree investigated. The results indicated that the nano-composite catalyst showed very high photocatalytic activity. When the amount of catalyst is controlled 1.5 g/L and the initial concentration of the dye is 20 mg/L in pH=3 system, the degradation efficiency of methyl violet was 98.13%. When the amount of catalyst is controlled 4.0g/L and the irradiation time is 12 h, the degradation efficiency of phenol was 73.52%. The phenol degradation rate reached 88.73% after 12 h with adding trace H2O2.3. The kinetic model of the photocatalystic degradation reaction of methyl violet and phenol had been researched and the possible energy transfer mechanism had been discussed also.更多还原