煅烧温度对掺杂二氧化钛纳米粉末可见光响应的影响

发布时间：2018-01-12 00:07

  本文关键词：煅烧温度对掺杂二氧化钛纳米粉末可见光响应的影响　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： TiO2 温度 掺杂 可见光

【摘要】：随着工业化不断深入发展,城市环境污染日益严重,而TiO2光催化降解有机污染物技术为解决该问题提供了有效方案。纯TiO2量子产率低且带隙太宽无法产生可见光响应,研究表明氮掺杂TiO2可将吸收波长从紫外光区拓展到可见光区,但是不同方法制备的TiO2其可见光性能具有很大差异,其响应机理也存在一定争议,因此具有可见光响应的二氧化钛仍然停留在试验阶段。本文为了进一步促进TiO2的商业化应用,对TiO2的掺杂工艺进行了深入的研究,通过调控煅烧温度来实现高效可见光响应TiO2的工艺开发。在氮掺杂工艺的基础上,本文对比研究了煅烧温度对氮氢共掺杂改性样品的影响,以探索出更优异的制备工艺。在具体的研究过程中,考察了煅烧温度对氮掺杂以及氮氢共掺杂样品的晶型结构、表面形貌、光学性能以及可见光下光催化性能的影响,主要成果如下:1.随着煅烧温度的提高氮掺杂样品其掺杂浓度迅速升高,其掺杂位置也从间隙位逐渐过渡到取代位,可见光响应能力逐渐增强。氮掺杂浓度的升高可能会促进样品表面或者内部大量氧空位等缺陷的产生,作为光生载流子的复合中心降低了光生电子空穴的分离效率,反而会抑制其可见光下光催化活性。2.相比单一氮掺杂工艺,氮氢共掺杂样品在煅烧温度提升中能保持更稳定的氮掺杂浓度以及相稳定性,并在样品表面形成一层非晶层。随着煅烧温度的提高,其可见光响应能力提升相对更缓慢,但是光生电子空穴的分离效率相比氮掺杂样品更高,从而使低温掺杂样品具有更好的光催化性能。3.当煅烧温度过高时会伴随TiN的生成,虽然会大幅提升TiO2的可见光响应能力,但作为非辐射复合的中心促进大量光生电子空穴的复合,对可见光降解苯的性能极其有害。因此,无论是单一氮掺杂还是氮氢共掺杂其煅烧工艺都需要控制在600℃以下,从而保证样品具有很好的可见光催化性能。
[Abstract]:With the deepening development of industrialization, urban environmental pollution is becoming more and more serious. TiO2 photocatalytic degradation of organic pollutants provides an effective solution to this problem. The pure TiO2 quantum yield is low and the band gap is too wide to produce visible light response. The results show that the absorption wavelength of nitrogen-doped TiO2 can be extended from the ultraviolet region to the visible region, but the visible light properties of TiO2 prepared by different methods are very different, and its response mechanism is also controversial. Therefore, titanium dioxide with visible light response is still in the experimental stage. In order to further promote the commercial application of TiO2, the doping process of TiO2 is deeply studied in this paper. On the basis of nitrogen doping process, the effect of calcination temperature on nitrogen-hydrogen co-doped modified samples was studied. In order to explore a better preparation process. In the specific research process, the crystal structure and surface morphology of N-doped and nitrogen-co-doped samples were investigated. The main results are as follows: 1. With the increase of calcination temperature, the doping concentration of nitrogen-doped samples increases rapidly. The doping position also gradually transition from gap site to substitution site, and the visible light response ability is gradually enhanced. The increase of nitrogen doping concentration may promote the generation of defects such as a large number of oxygen vacancies on or inside the surface of the sample. As the composite center of photogenerated carriers, the separation efficiency of photogenerated electron holes is reduced, but the photocatalytic activity of photocatalytic activity under visible light is inhibited. 2. Compared with the single nitrogen doping process. The nitrogen-hydrogen co-doped sample can maintain more stable nitrogen doping concentration and phase stability in the calcination temperature, and form a layer of amorphous layer on the surface of the sample, with the increase of calcination temperature. The enhancement of visible light response ability is slower, but the separation efficiency of photogenerated electron hole is higher than that of nitrogen doped sample. Thus, the low-temperature doped samples have better photocatalytic performance .3.When the calcination temperature is too high, the formation of TiN will be accompanied, although it will greatly improve the visible light response ability of TiO2. However, as the center of non-radiation recombination, it promotes the recombination of a large number of photogenerated electron holes, which is extremely harmful to the degradation of benzene by visible light. The calcination process of either single nitrogen doping or nitrogen hydrogen co-doping needs to be controlled below 600 鈩，

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