【作者】 刘立嫱；

【导师】 全燮；

【作者基本信息】 大连理工大学 ， 环境工程， 2010， 硕士

【摘要】 纳米TiO2光催化技术已经得到广泛研究。阳极氧化法制备的TiO2纳米管阵列具有较大比表面积和较强的吸附能力,与钛基体结合牢固等优点,表现出比TiO2纳米膜更高的光催化活性和光电转化效率,对TiO2纳米管阵列进行合理改性进一步提高其光催化活性具有重要意义。金属元素掺杂是改善TiO2光催化活性的一种有效方法。为此,制备了金纳米晶负载和铁掺杂TiO2纳米管阵列电极,并对制备的光电极进行了系统表征和光催化活性研究。同时,为实现纳米TiO2产业化,对水热法制备TiO2纳米纤维进行了研究。本论文围绕以上内容,主要开展了以下几个方面的工作：(1)采用电化学自掺杂法制备了Au纳米晶负载TiO2纳米管阵列复合电极。电极为阵列结构,平均孔径为100nm,平均管长为7μm。X射线衍射(XRD)、X射线荧光光谱分析(XRF)和紫外-可见漫反射光谱(DRS)分析显示,500℃煅烧制得的电极为锐钛矿相；Au的掺杂量为0.05wt.%；在400nm-700nm产生一个明显的Au纳米晶表面等离子共振吸收带,电极在可见光区具有明显的吸收峰。可见光下,Au/TiO2纳米管阵列复合电极6小时可降解亚甲基蓝(10ppm)达85%以上,而未负载的TiO2纳米管阵列基本未降解,其在可见光下表现出良好的光催化性能。(2)以阳极氧化TiO2纳米管阵列为基底,采用超声震荡法制备了铁掺杂的TiO2纳米管阵列。由DRS及SPV分析可知铁掺杂增强了TiO2纳米管阵列对可见光的吸收和光生电了-空穴对的分离能力。铁掺杂TiO2纳米管阵列的光催化实验表明,紫外光照射2小时可降解亚甲基蓝(10ppm)达90%,可见光照射6小时降解40%,表现出良好的光催化活性。但当铁掺杂过量,会产生抑制作用。(3)应用水热法制备了TiO2纳米纤维。制备的TiO2纳米纤维直径为50nm左右,长度为20μm。由透射电镜图(TEM)可以看出实验过程中经酸冲洗浸泡和煅烧后,纳米纤维的结构没有被破坏。300-450℃煅烧可得到锐钛矿相TiO2。在紫外光下催化降解亚甲基蓝(10ppm),80分钟降解率达90%。更多还原

【Abstract】 Titanium dioxide (TiO2) with nanostructure has been studied as photocatalyst in degradation of organic pollutants for decades. TiO2 nanotube arrays prepared by anodization method possess great specific surface area, prominent absorption ability and strong mechanical strength, thus exhibit better PC performance and higher photoelectron conversion efficiency than TiO2 nano film. However, it is very important to further improve its photocatalytic activity by reasonable doping. It has been proved that metal doping would be a viable way to improve the photocatalytic activity of TiO2. In the present work, Au nanocrystal anchored TiO2 nanotube array electrode and iron doped TiO2 nanotube array electrode were prepared and characterized. In addition, to realize the industrialization of nano TiO2, TiO2 nanofibers prepared by hydrothermal method were studied and characterized. Based on the mentioned above, some works were carried out as follows:(1) Au nanocrystal anchored TiO2 nanotube array electrode was prepared by electrochemical self-doping method. The electrodes presented compact array configuration with an average pore diameter of approximately 100 nm and a length approximately 7μm. Au nanocrystal anchored TiO2 nanotube array electrode analyzed by X-ray fluorescence spectroscopy (XRF) were 0.05wt.%. X-ray spectra (XRD) indicated that the crystal structure of Au/TiO2 electrode prepared at 500℃was pure anatase phase. UV-vis absorption spectra (DRS) showed a broad absorption band in the 400nm-700nm region because of plasma resonance absorption of ultrafine Au nanocrystal. Under visible light irradiation, the photodegradation of methylene blue (MB, 10ppm) on Au/TiO2 electrode was more than 85% in 6h.(2) Fe-doped TiO2 nanotube array electrode was prepared by immersing TiO2 nanotube array in iron salt solution under ultrasonic condition. The DRS and SPV analysis showed noticeable increase of visible light absorption and excellent separation of ability of electron-hole pair of Fe-doped TiO2 nanotube array electrode. Under UV light irradiation, the photodegradation of MB (10ppm) on Fe/TiO2 electrode was more than 90% in 2 h, while visible light irradiation,40% photodegradation efficiency was obtained in 6h. Fe-doped TiO2 nanotube array electrode exhibited excellent photocatalytic activity, but excess iron doping, its photocatalytic activity was decreased. (3) TiO2 nanofibers with diameter of approximately 50nm and length of approximately 20um were prepared by hydrothermal method. During the process of acid washing and calcination, the structure of nanofibers was not damaged. After 300-450℃calcination, they were anatase phase. Under UV light irradiation, the photodegradation of MB was 90% in 80min.更多还原