镧掺杂二氧化钛纳米管微波法制备及光催化性能研究

发布时间：2018-06-18 16:24

本文选题：微波法 + 镧掺杂　；参考：《重庆大学》2010年硕士论文

【摘要】： 纳米材料的概念是在20世纪中叶被科学界提出的,是当今新型材料,并日益得到广泛重视和深入研究,是新材料研究中最富有活力,对社会、经济发展有着重要影响的研究对象。目前,纳米材料已经在化工、国防、电子、医学等领域展示出良好、实质的应用前景。纳米TiO_2是一种氧化能力强、无毒无害、反应速度快、降解效率较高、无二次污染的新型光催化剂,因其优异的光学性能、催化性能和光电转换性能,引起人们极大关注。其中,TiO_2纳米管具有更大的比表面积,在光催化降解大气和水中的污染物、清洁能源等方面有广阔的应用前景。本文研究的微波合成法是利用微波对水的介电作用进行合成,是一种新型合成纳米管的方法,其合成机理尚不明确,且存在很多争议。与传统方法相比,微波法具有反应灵敏、加热速度快、受热体系均匀等优点。但现阶段而言,国内外对其报道极少,对掺杂TiO_2纳米管的微波法制备及光催化性能研究更是少有提及。本文利用溶胶-凝胶法制备了镧掺杂纳米粉,并且以纳米粉为前驱物,利用微波制备了稀土镧掺杂的TiO_2纳米管,同时对它们进行光催化性能对比。利用场发射扫描电子显微镜、透射电子显微镜、比表面仪、荧光光谱仪和X射线衍射仪等对试样形貌、结构和组成进行表征,并对其形成机理进行分析。结果表明:利用溶胶-凝胶法制备的作为前驱物的TiO_2纳米粉体粒径在40~60nm之间,掺杂使纳米粉体的颗粒形状更不规则,其颗粒表面更加粗糙,导致比表面积增加。利用微波法以TiO_2纳米粉为前驱物,可以制得形貌比较完整的TiO_2纳米管,掺杂镧的TiO_2纳米管外径约为8~20nm,内径约为6~18nm,长约50~100nm;未经HCl酸洗的TiO_2纳米管在电镜下非常完整,而经过HCl酸洗的TiO_2纳米管在电镜下观察则发现其局部遭到破坏。TiO_2纳米管的形成可用纳米粉体在微波和NaOH的共同作用下首先解离为TiO_2纳米薄片,TiO_2纳米薄片经卷曲形成纳米管进行解释。以甲基橙为目标降解物,研究了锐钛矿型纳米TiO_2的光催化性能。纳米TiO_2试样在15W紫外光源照射下,经150min光催化降解试验,结果表明:TiO_2纳米管比纳米粉具有更好的光催化性能;镧掺杂TiO_2纳米管存在一个合理掺杂量,本试验条件下的最佳掺杂量为0.5%,其降解率可达到55.28%。本研究通过稀土元素掺杂TiO_2纳米管进一步提高了纳米TiO_2光催化性能,为其在诸多领域得到广泛而又实质性应用提供了一种新的途径。
[Abstract]:The concept of nanomaterials was put forward by the scientific community in the middle of the 20th century. Economic development has an important impact on the object of study. At present, nanomaterials have shown good and substantial application prospects in chemical industry, national defense, electronics, medicine and other fields. Nano-TiO2 is a new photocatalyst with strong oxidation ability, innocuity, fast reaction rate, high degradation efficiency and no secondary pollution. Because of its excellent optical performance, catalytic performance and photoelectric conversion performance, it has attracted much attention. Among them, tio _ 2 nanotubes have a larger specific surface area and have a broad application prospect in photocatalytic degradation of pollutants in atmosphere and water, clean energy and so on. The microwave synthesis method studied in this paper is a new method of synthesizing nanotubes by using microwave to synthesize the dielectric action of water. The mechanism of synthesis is not clear and there are many controversies. Compared with the traditional method, microwave method has the advantages of sensitive reaction, fast heating speed and uniform heating system. However, at present, there are few reports at home and abroad, and the preparation of TiO-2 nanotubes by microwave method and the study of their photocatalytic properties are seldom mentioned. In this paper, lanthanum doped nanocrystals were prepared by sol-gel method, and the rare-earth lanthanum-doped TIO _ 2 nanotubes were prepared by microwave using nanometer powders as precursors, and their photocatalytic properties were compared. The morphology, structure and composition of the samples were characterized by field emission scanning electron microscope (SEM), transmission electron microscope (TEM), specific surface analyzer, fluorescence spectrometer and X-ray diffractometer, and the formation mechanism was analyzed. The results show that the particle size of TIO _ 2 nanoparticles prepared by sol-gel method is in the range of 40~60nm, and doping makes the particle shape more irregular and the surface roughness, resulting in the increase of specific surface area. Using TiO2 nano-powder as precursor, TiO2 nanotubes with relatively complete morphology can be prepared by microwave method. The outer diameters of La doped TiO2 nanotubes are about 820 nm, and the inner diameters of TiO2 nanotubes are about 60.18 nm, and the length of TiO2 nanotubes is about 50 ~ 100nm.The unHCl acid-pickled TiO2 nanotubes are very complete under electron microscope. On the other hand, after HCl acid pickling, the TIO _ 2 nanotubes were observed under electron microscope. The formation of TiO2 nanotubes can be separated into TiO2 nanoplates by curl shape under the combined action of microwave and NaOH. Into nanotubes to explain. The photocatalytic properties of anatase nano-TiO _ 2 were studied with methyl orange as the target degradation material. The photocatalytic degradation of TiO2 nanotubes was studied by 150min photocatalytic degradation under 15W UV irradiation. The results showed that: TiO2 nanotubes have better photocatalytic properties than nano-powders, and La doped TiO2 nanotubes have a reasonable amount of doping. The optimum doping amount is 0.5 and the degradation rate can reach 55.28. In this study, TiO-2 nanotubes doped with rare earth elements further improved the photocatalytic properties of TiO-2 nanotubes, which provided a new way for its extensive and substantive application in many fields.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TB383.1

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