二氧化钛基纳米材料的制备及其光催化降解、产氢特性研究

发布时间：2018-04-13 03:21

本文选题：静电纺丝 + 自燃烧法　；参考：《兰州大学》2015年硕士论文

【摘要】：随着社会的不断发展和进步,环境污染和能源危机已成为全球关注的焦点问题。为了治理及防治环境污染,研究者们正在努力研究和寻求一种既能满足人们的需求又不能对环境构成新威胁的方法。半导体光催化的出现为研究者们解决上述问题提供了新思路。在众多半导体材料中,Ti02因其氧化能力强,物理化学性质稳定,自然界储存丰富,被广泛应用于光催化降解有机污染物以及光解水制氢中。然而作为光催化剂,Ti02也存在本征性缺点：带隙过宽导致只能利用紫外光；电子空穴复合较快严重影响Ti02的光催化效率。本论文通过分析Ti02光催化剂存在的问题,有针对性的开展了以下两个工作。第一提出通过静电纺丝制备TiO2@SnO2异质结纳米管,抑制电子空穴的复合,有效提高光催化效率；第二提出通过自燃烧法制备纳米泡沫状Ti02,利用其大的比表面积,增强太阳光吸收能力,以及锐钛矿与金红石混合相有效分离电子空穴对,从而改善光催化特性。通过上述两种光催化剂性质的研究,对Ti02基光催化机理进行了深入探讨,获得了一些研究成果,结果如下：1.利用静电纺丝技术一步法成功制备出TiO2@SnO2异质结纳米线和纳米管。通过调控退火升温速率,1℃/min时获得TiO2@SnO2异质结纳米线,纳米线直径为200 nm左右,6℃/min时得到TiO2@SnO2异质结纳米管,纳米管直径大约为200 nm,从TEM中可以看到异质结纳米管的管壁厚度大约为20 nm。将TiO2@SnO2异质结纳米线作为光催化剂,降解RhB染料,通过调控前驱物原料比例,发现当SnCl2·2H2O与钛酸四丁酯的质量比为2：1时,光催化效果最佳。同样条件下,TiO2@SnO2异质结纳米管表现出了更高的光催化降解效率,这归因于异质结纳米管拥有更大的比表面积,能够吸附大量的染料分子,管状结构所特有的陷光效应,以及TiO2和SnO2两相之间形成的异质结结构,大大提高了光生电子空穴对的分离效率。通过制备工艺的广泛研究,对静电纺丝技术制备TiO2@SnO2异质结纳米管的形成机制进行了深入分析,我们提出了聚合物自模板法机理,很好的解释了纳米管的形成过程。预期该机制可推广到静电纺丝技术获得其它纳米管的研究当中。2.通过简单的一步自燃烧法制得了纳米泡沫状Ti02样品,并研究了纳米泡沫Ti02的光催化降解RhB染料和光解水制氢的性质。通过研究表明纳米泡沫Ti02的光催化效果明显高于商用P25材料：30 nim后样品Ti02 NF 0.8g作为光催化剂时,RhB燃料被完全降,而当P25作为光催化剂时,仍然还有5%的RHB燃料没有被降解；经过4h的光解水制氢,泡沫TiO2的平均制氢量是商用P25的1.2倍。这主要是由于纳米泡沫Ti02具有更大的比表面积可吸附更多的染料分子；泡沫状陷光结构也捕获了大量的光子,有效提高了太阳光的利用率；泡沫TiO2的吸光范围拓宽,相比商用P25吸收边红移；锐钛矿相与金红石相所形成的同质结增强电子空穴对分离；泡沫Ti02的光电流测试也说明载流子浓度增加,电子空穴对分离效率提高。这些综合因素导致纳米泡沫TiO2拥有更强的光催化降解和光解水产氢能力。
[Abstract]:With the development and progress of society , environmental pollution and energy crisis have become the focus of global attention . In order to control and control environmental pollution , researchers are trying to study and seek a new method which can not only meet the needs of people but also can not pose new threats to the environment . In many semiconductor materials , Ti02 has been widely used in photocatalytic degradation of organic pollutants and photodissociation of organic pollutants .
The photocatalytic efficiency of Ti02 was seriously affected by electron hole recombination . In this paper , by analyzing the problems of Ti02 photocatalyst , the following two tasks were carried out . First , the TiO2 @ SnO2 heterojunction nanotube was prepared by electrostatic spinning , and the recombination of electron holes was inhibited , and the photocatalytic efficiency was effectively improved ;
The TiO2 @ SnO2 heterojunction nano - nano - tubes were prepared by self - combustion method . The results were as follows : 1 . TiO2 @ SnO2 heterojunction nano - nano - tubes were prepared by one - step method .
The average hydrogen production capacity of TiO _ 2 was 1.2 times higher than that of commercial one . This was mainly due to the greater specific surface area of nano - foam Ti02 to adsorb more dye molecules .
the bubble trap structure also captures a large number of photons , thereby effectively improving the utilization rate of the sunlight ;
the absorption range of the foam TiO2 is widened , and the absorption edge of the foam TiO2 is shifted by the absorption edge ;
homogeneous junction enhanced electron hole pair separation formed by anatase phase and rutile phase ;
The photocurrent test of foam Ti02 also shows that the carrier concentration is increased , and the separation efficiency of the electron hole is improved . These factors lead to the stronger photocatalytic degradation and photodissociation water - producing ability of the nano - foam TiO2 .

【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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