纳米二氧化钛光催化剂的工艺及使役行为研究

发布时间：2018-01-20 10:35

本文关键词： 二氧化钛可见光吸收光催化氢化氮掺杂氧空位　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：由于良好的化学稳定性、无毒性、抗光腐蚀、价格低廉等优点,TiO2被广泛地应用于光催化、太阳能电池、空气和水的净化等方面。因此,纳米二氧化钛光催化剂在环境净化和能源开发等方面具有重要的作用和广阔的前景。但是,TiO2的宽带隙(锐钛矿约为3.2eV,金红石约为3.0eV)导致其只能吸收仅占太阳光的3%~5%的紫外光,极大地限制了TiO2的量子产率。所以,克服TiO2光催化剂的局限性,提高TiO2在可见光照射下的光催化活性具有重要的意义。首先,本文在不同的热处理条件下,如不同的气氛、通气时间,尤其是改变退火过程中的通气顺序(NH3/H2和H2/NH3),得到一系列纳米二氧化钛光催化剂,分别为:H-TiO2,N-TiO2,N-H-TiO2,H-N-TiO2。然后,本文从结构、成分、光吸收及缺陷组成等方面探究了纳米TiO2光催化剂之间的差异性,进而对N掺杂和氢化的作用机理进行了分析和讨论。最后,本文研究了光催化测试过程的各个参数(催化剂的用量及苯的初始浓度等)对N-H-TiO2光催化剂在实际应用中的影响,并对N-H-TiO2进行稳定性测试。本文首次从一个崭新的角度研究了TiO2的制备工艺及其使役行为。与单一气氛下退火得到的样品(H-TiO2和N-TiO2)和先氢化后N掺杂得到的H-N-TiO2相比,先N掺杂后氢化得到的N-H-TiO2光催化剂具有最优异的性能。在可见光照射下,100mg N-H-TiO2光催化剂在3小时内能够将初始浓度为200ppm左右的苯彻底降解。N-H-TiO2和H-N-TiO2之间结构和性能的差异性来源于高温退火过程中氨气和氢气通入顺序的不同。N-H-TiO2的可见光催化活性高是因为其结晶度高,颗粒尺寸小,光吸收能力强,光生载流子的分离速率快,以及表面无序层和氧空位等缺陷造成的表面吸附能力强等因素的综合作用。N掺杂和氢化的顺序不同还会影响N掺杂的位置(间隙位或者取代位)及其浓度。另外,延长氢化时间能够明显提高TiO2对苯的矿化作用。N-H-TiO2具有持续的光催化活性和稳定性,具有良好的实际应用价值。
[Abstract]:TIO _ 2 is widely used in photocatalysis, solar cells, air and water purification due to its good chemical stability, non-toxicity, anti-photocorrosion and low cost. Nanometer TIO _ 2 photocatalyst has important role and broad prospect in environmental purification and energy development, but the wide band gap of TIO _ 2 (anatase is about 3.2 EV). Rutile (about 3.0 EV) can only absorb 3% of UV light, which greatly limits the quantum yield of TiO2. Therefore, the limitation of TiO2 photocatalyst is overcome. It is important to improve the photocatalytic activity of TiO2 under visible light irradiation. Firstly, under different heat treatment conditions, such as different atmosphere, ventilation time. In particular, a series of nano-TiO _ 2 photocatalysts were obtained by changing the aeration order of NH _ 3 / H _ 2 and H _ 2 / NH _ 3 during annealing. N-H-TiO2 and H-N-TiO2.Then, the differences between nano-sized TiO2 photocatalysts were discussed in terms of structure, composition, light absorption and defect composition. Then the mechanism of N doping and hydrogenation is analyzed and discussed. Finally. In this paper, the effects of various parameters (amount of catalyst and initial concentration of benzene) on the application of N-H-TiO _ 2 photocatalyst were studied. And the stability of N-H-TiO _ 2 was tested. The preparation process and causative behavior of TiO2 were studied for the first time from a new point of view, which was compared with the sample annealed in a single atmosphere. H-TiO _ 2 and N-TiO _ 2) were compared with H-N-TiO _ 2 prepared by hydrogenation and then N doping. N-H-TiO _ 2 photocatalyst prepared by N-doping and hydrogenation has the best performance. 100mg. Source of structure and performance differences between N-H-TiO _ 2 and H-N-TiO _ 2 photocatalysts for complete degradation of benzene with initial concentration of 200ppm within 3 hours. The visible light catalytic activity of ammonia and hydrogen in different order during high temperature annealing is high because of its high crystallinity. The particle size is small, the light absorption ability is strong, and the separation rate of photogenerated carriers is fast. As well as the surface disordered layer and oxygen vacancy and other defects caused by the surface adsorption ability and other factors. The order of N doping and hydrogenation will also affect the position of N doping (gap or substitution sites). And its concentration. Prolonging the hydrogenation time can obviously improve the mineralization of benzene by TiO2. N-H-TiO _ 2 has continuous photocatalytic activity and stability, and has good practical application value.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ134.11;TB383.1

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