【作者】 李月霞；

【导师】 黄佳木；

【作者基本信息】 重庆大学 ， 材料学， 2007， 硕士

【摘要】 二氧化钛半导体材料作为光催化的理想材料,得到了广泛的研究。这些研究都集中在对晶态TiO₂进行的一系列技术改性,极少有对非晶TiO₂的研究。而晶态TiO₂的制备存在需要进行热处理或者在线加温,同时对基材结构和耐温性能要求较高等难以克服的缺点。另外,由于TiO₂为宽禁带半导体,对太阳光的利用局限于紫外部分,离子掺杂可以实现半导体TiO₂的可见光吸收。因此,本文中,采用金属离子掺杂非晶态二氧化钛的方法提高非晶态二氧化钛的光催化活性。本文首先简要介绍了半导体光催化的基本原理,在总结和评述提高半导体光催化光量子效率和太阳能利用率的各种方法、研究进展、存在的主要问题的基础上,采用反应磁控溅射法在玻璃基片上制备非晶态TiO₂-M（M为Cr或V）薄膜。利用现代测试技术,如X射线衍射仪、紫外-可见光分光光度计、X光电子能谱仪、荧光光度计、薄膜厚度测试仪及原子力显微镜等,研究分析了薄膜的组分、结构、吸收光谱、荧光光谱、膜厚和表面形貌等。薄膜的光催化活性用薄膜对亚甲基蓝以及罗丹明B的降解率来表征,使用紫外灯作为照射源。考察了溅射温度、相对掺杂量、膜厚、目标降解物溶液pH值以及溶液中H2O2浓度等对非晶TiO₂-M薄膜光催化活性的影响。重点在揭示分析非晶TiO₂-M薄膜光催化活性的原因。XRD、XPS、AFM、可见-紫外吸收光谱等研究表明:TiO₂-M（M为Cr或V）薄膜为非晶态结构;薄膜的可见-紫外吸收光谱表明掺杂引起了TiO₂吸收带边的红移,并且计算证实了带隙的减小。适当的掺杂量可以产生新的吸收峰,增加对长波段光的吸收,提高光催化效率。分析认为,对非晶TiO₂进行适量的M掺杂能有效提高光生载流子在TiO₂半导体内部的扩散系数,使得非晶TiO₂-M半导体材料具有光催化活性。通过不同厚度薄膜对亚甲基蓝的光催化降解试验发现,本试验得到的非晶态TiO₂-Cr薄膜厚度的阈值为114nm,非晶态TiO₂-V薄膜厚度的阈值为129nm,TiO₂-M（M为Cr或V）薄膜分别在该值范围内,薄膜的光催化活性随膜厚的增加而增强。超过此阈值后,光催化活性不再增加。更多还原

【Abstract】 Titanium dioxide is one of the most popular and promising material as photocatalyst for air treatment and detoxification of waste water. However, nearly all photocatalysic studies on TiO₂ have focused on its crystalline forms, as it is commonly accepted that amorphous TiO₂ has a rapid electron-hole recombination. Nevertheless, crystalloid TiO₂ puts high demand upon preparation temperature and the nature of the substrate. Meanwhile, Titanium dioxide is a semi-conductor with wide band gap, and its photocatalysis operates only when it is irradiated under the ultraviolet radiation of sunlight. Impurity doping of TiO₂ with metal ions can extend light absorption of TiO₂ fairly to the visible region. So, in this paper, we will study the amorphous meatal doped TiO₂ film to improve its photocatalytic activity.In this dissertation, the basic principle about semiconductor photocatalysis was reviewed briefly at first. The methods, research progress and main problems about improving the total quantum-effciency and utilization efficiency of solar energy for semiconductor photocatalysis have been summarized, thedisadvantages and the developing trends about the preparation route of nanosized crystalline TiO₂. Then, a series of TiO₂-M（M is Cr or V）films were prepared at room temperature by reactive magnetron sputtering.The films were investigated by atom microscope, X-ray diffractometer, X-ray photoelectron spectroscopy, UV-Vis spectrophotometer, the photoluminescence （PL） and ellipse polarization apparatus. The photocatalytic properties of these fims were characterized by the decomposition rate of methylene blue or rhodamine B. The effect of doping sputtering power, film thickness, sputtering temperature and the content of adscititious oxidant such as H2O2 and pH value in aqueous Rhodamine B were discussed. And the influence of amorphous metal doped TiO₂ film’s photocatalytic activity was principally investigated.The results indicated that TiO₂-M film exists in the form of amorphous. It possessed a band gap of less than 3.20eV, and an appropriate doping imported a new absorption peak. The facts suggest that M-doped （M is Cr or V）results in a great increase in the photocatalytic activity of amorphous TiO₂ films.The probable reason may be that an appropriate chrome doping quantity can led to a rapid increase of photoconduction. The experiments of decomposing methylene blue and Rhodamine B with the films show that the films exhibited excellent photocatalytic activities. As a result, the thickness threshold on TiO₂-Cr film is 114 nm, While, TiO₂-V film is 129 nm, when the thickness is over this numerical number, the rate of photodegradation becomes stable.更多还原