二氧化钛纤维光催化合成氨

发布时间：2018-02-09 12:42

本文关键词： TiO_2纳米纤维非晶态合金单掺杂共掺杂合成氨光催化　出处：《海南大学》2017年硕士论文　论文类型：学位论文

【摘要】：纳米TiO_2与其他的半导体材料相比,可以催化多种的污染物,而且反应条件温和,操作简单,被广泛应用于废水处理、室内空气净化等领域,具有催化活性高、化学性质稳定等优点,是一种非常具有发展前景的光催化材料。但TiO_2作为光催化材料,存在着比较明显的不足:一是TiO_2粉体尺寸小,不易回收,而且它的禁带宽度大(Eg = 3.2 eV),只有在紫外光的照射下才能被激发,不能充分的利用太阳能;二是它的光生电子和空穴极易复合,光电子效应差,这些不利因素都限制了 TiO_2的广泛应用。本文以介孔SiO_2球为模板,TiCl_4为前躯体,气相生长制备了高催化活性的TiO_2纳米纤维,不仅解决了其不易回收、光生电子和空穴易复合的问题,而且通过Fe、V、N离子的掺杂,扩宽了光响应范围至可见光区,具有非常重要的意义。实验结果表明:制备的TiO_2纳米纤维为锐钛矿,直径在7-10 nm,紫外光下合成氨的结果表明,纤维的光催化活性要高于P25。经过非晶态合金(Ni-Mo-B)修饰的纳米纤维,荧光强度进一步降低,对可见光的吸光强度进一步增强,而且也没有改变纤维的晶型和形貌,合成氨的收率也得到了提高。为了提高TiO_2纳米纤维在可见光下的光催化活性,对纤维进行了单离子和共离子的掺杂改性,实验结果表明,经过单离子N、Fe、V改性后,纤维的晶型和形貌没有发生改变,但是荧光强度降低,吸收带发生了红移,合成氨的收率得到了很大的提高。经过共掺杂改性后,表征结果还要优于单掺杂改性,而且进一步提高了纤维的光催化活性。
[Abstract]:Compared with other semiconductor materials, nanometer TiO_2 can catalyze a variety of pollutants, and the reaction conditions are mild, the operation is simple, and it is widely used in wastewater treatment, indoor air purification and other fields, with high catalytic activity. Because of its stable chemical properties, TiO_2 is a very promising photocatalytic material. However, as a photocatalytic material, TiO_2 has obvious disadvantages: first, the size of TiO_2 powder is small, and it is difficult to recover. Moreover, it has a wide band gap E g = 3.2 EV, which can only be excited by ultraviolet light, and can not make full use of solar energy. Second, its photogenerated electrons and holes are easily recombined, and the photoelectron effect is poor. These disadvantages limit the wide application of TiO_2. In this paper, TiO_2 nanofibers with high catalytic activity were prepared by gas phase growth using mesoporous SiO_2 spheres as template and TiCl4 as precursor. The problem of easy recombination of photogenerated electrons and holes, and the wide range of light response to visible light by doping Feo / VN ions are of great significance. The experimental results show that the prepared TiO_2 nanofibers are anatase. The results of ammonia synthesis under ultraviolet light with diameter of 7-10 nm show that the photocatalytic activity of the fiber is higher than that of P25.The fluorescence intensity of the modified nanofibers modified by amorphous alloy Ni-Mo-B- () is further reduced, and the absorption intensity of visible light is further enhanced. In order to improve the photocatalytic activity of TiO_2 nanofibers under visible light, the single ion and co-ion doping modification was carried out, and the experimental results showed that, in order to improve the photocatalytic activity of TiO_2 nanofibers, the morphology and morphology of the fibers were not changed. After modification by single ion, the crystal shape and morphology of the fiber have not changed, but the fluorescence intensity has decreased, the absorption band has shifted red, and the yield of ammonia has been greatly improved. After co-doped modification, the yield of synthetic ammonia has been greatly improved. The characterization result is better than that of single doping modification, and the photocatalytic activity of the fiber is further improved.
【学位授予单位】：海南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ113.2

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