【作者】 秦德昭；

【导师】 李华基；

【作者基本信息】 重庆大学 ， 材料加工工程， 2011， 硕士

【摘要】 纳米材料所产生的小尺寸效应、界面效应和宏观量子隧道效应等使其在光、电、热、磁等物理性质和化学性质方面与常规材料相比,具有了许多奇异特性和新的特殊功能。以纳米半导体氧化物为催化剂的多相光催化是一种理想的环境污染治理技术,已成为近年来国际上最为活跃的研究领域之一。纳米TiO₂以其氧化能力强、无毒无害、降解效率较高、无二次污染和成本低的特点而最为常用。TiO₂纳米管具有比纳米粉体和薄膜更大的比表面积,纳米管的大比表面积提供了更多的反应活性位,更有利于需降解物质的吸附和反应;管状结构为电子的迁移和界面间的电荷转换提供了好的通道。利用稀土元素独特的4f电子结构,对TiO₂进行稀土元素掺杂改性是常用的提高TiO₂光催化活性的方法。纵观目前众多的稀土掺杂TiO₂光催化研究,大都是单一稀土元素掺杂,稀土元素与过渡金属元素或非金属元素的双元素共掺杂,对双稀土混合掺杂研究报道极少。本文采用溶胶-凝胶法成功制备了稀土镧铈混合掺杂TiO₂纳米粉体。并且以该纳米粉为前驱物,利用微波法制备了稀土镧铈混合掺杂的TiO₂纳米管,同时对它们进行光催化性能对比。利用透射电子显微镜（TEM）、X射线衍射仪（XRD）和X射线荧光光谱（XRF）等手段对试样形貌、结构和组成进行表征,并对其形成机理进行分析。以染料甲基橙为光催化反应模型化合物,分析了制备和降解等工艺对有机物光催化降解的影响。结果表明:1.溶胶-凝胶法制备的TiO₂粉体颗粒均匀,粒径在10-20nm之间。掺杂对粉体的粒径有较大影响,掺杂后的粉体粒径比未掺杂的粒径小,说明掺杂抑制了纳米晶体的生长。稀土离子掺杂还可以抑制相变,提高了TiO₂由锐钛矿型转变为金红石型的温度。2.以TiO₂纳米粉为前驱物,采用微波法可以制得形貌比较完整的TiO₂纳米管。在电镜下观察到,TiO₂纳米管是开口、中空管,直径基本一致,掺杂镧铈的TiO₂纳米管外径约为10-15nm,内径约为4⁸nm,长约50⁸0nm。3.以甲基橙为目标降解物,在15W紫外光源照射下,经150min,对纳米粉和纳米管材料进行了光催化研究,实验结果表明,La、Ce共掺提高了TiO₂纳米粉和纳米管的光催化活性。活性的提高可以归功于以下几个有利作用:在紫外可见范围的强烈吸收、氧空穴的生成、表面吸附能力的增强等。更多还原

【Abstract】 Compared with conventional materials, nano-materials have many singular features and new special features because of their small size effect, interface effect and macroscopic quantum tunnel effect on the optical, electrical, thermal, magnetic and other physical properties and chemical properties. Oxide semiconductor nano-catalysts heterogeneous photocatalysis is an ideal environment for pollution control technology, has become the most active international research areas in recent years. Nano-TiO₂ has been most commonly used with the characteristics of strong oxidizing ability, non-toxic harmless, the higher the degradation efficiency, low cost and no secondary pollution. TiO₂ nanotubes have a larger surface area than nanopowder and thin films, this surface area of nanotubes provides more reaction active sites so that degradation of material to be more conducive to the adsorption and reaction; tubular structure provids a good channel for electronic migration and interface charge transfer. Using the unique 4f electronic structure of rare earth elements, rare earth doped TiO₂ is commonly used to improve the photocatalytic activity of TiO₂. Looking at the current large number of rare earth doped TiO₂ photocatalytic studies, most are single rare earth doped, both rare earth elements and transition metals or non-metallic elements doped, mixed rare earth doped TiO₂ is minimal.Sol-gel method was used to prepare lanthanum cerium co-doped TiO₂ nanoparticles in this paper. To synthesis lanthanum cerium co-doped TiO₂ nanotubes by microwave based on the nano-powder precursor, while compared to the photocatalytic properties between them. Transmission electron microscopy （TEM）, X-ray diffraction （XRD） and X-ray fluorescence spectrometry （XRF） are used to characterize morphology, structure and composition of samples, and analyze its formation mechanism. To analyze the degradation process on preparation and photocatalytic degradation of organic matter by methyl orange as photocatalytic reaction model compounds. The results showed that:1. The TiO₂ nanoparticles which are prepared by sol-gel is evenly, and the diameter is between 10-20nm. The dopant have a great impact on the nanoparticles size, the doped nanoparticles size is smaller than the undoped, which illustrates that the growth of nanocrystals is restrained. Rare earth ion doped can restrain the phase transition, which can raise the TiO₂ transition temperature from anatase to rutile.2. To TiO₂ nanoparticles as the precursor, the relatively complete morphology of TiO₂ nanotubes can be prepared by microwave. TiO₂ nanotubes are open, hollow tube, almost the same diameter by observed in the electron microscope, the outer diameter of La-Ce co-doped TiO₂ nanotubes is 10-15nm, the inner diameter is 4-8nm, and the length is about 50-80nm.3. To methyl orange as target degradation, the nanopowder and nanotube are studied about photocatalytic by the 15W UV light irradiation at 150min, the result show that La-Ce co-doped improves the photocatalytic activity of TiO₂ nanoparticles and nanotubes. The high activity is due to the strong absorption of UV-visible range, the formation of oxygen hole, the enhanced adsorption capacity and so on.更多还原