贵金属掺杂和表面修饰对氧化物半导体气敏性能影响的研究

发布时间：2018-05-22 12:15

本文选题：气体传感器 + 掺杂　；参考：《吉林大学》2017年硕士论文

【摘要】：随着社会的不断发展与科技的不断进步,人们也越来越看重生活质量。在日常生活中难免会遇到一些有毒有害、易燃易爆气体,会对人身和财产造成危害。这时,气体传感器就会起到一个非常重要的作用,它能够及时的检测环境中的气体氛围。如今,科研工作者们致力于研制高性能、快速响应恢复和高选择性的气体传感器。在众多气体传感器中,金属氧化物半导体式气体传感器是目前最主要的一种气体传感器。它有着制备工艺简单、成本低、气敏性能很好等优点。目前,人们尝试不同的方法来合成氧化物半导体材料。而纯的氧化物半导体材料在气体传感器上的应用,存在着一些缺陷,如灵敏度不高,响应恢复慢,选择性不好等缺点。这样,人们从改善材料形貌、掺杂、表面修饰以及材料的复合等方面改进金属氧化物半导体气体传感器性能。本文以提高材料的气敏性能为出发点,利用贵金属对金属氧化物半导体进行表面修饰或者掺杂,并且制备出相应的气体传感器。利用X射线衍射分析(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及能量色散X荧光光谱(EDX)等表征手段,来分析材料的组成和形貌。本论文主要包含以下三个部分:第一,通过静电纺丝方法合成二氧化锡(SnO_2)纳米纤维,并利用湿法修饰方法修饰贵金属金(Au),同时对SnO_2纳米纤维材料和Au-SnO_2纳米纤维进行甲醛气敏性能测试。其中,相对于SnO_2纳米纤维材料,Au-SnO_2材料的响应度提高了2倍,而且有较低的工作温度,以及更好的选择性。第二,利用静电纺丝方法制备不同贵金属银(Ag)含量掺杂铁酸镧(LaFeO_3)纳米纤维,对比材料的甲醛气敏性能,以找出提高气敏性能的最佳Ag掺杂比。通过贵金属Ag掺杂之后的LaFeO_3纳米纤维材料有着更好的甲醛气敏特性,其中2 mol%Ag掺杂时,有着最好的气敏特性。此时,对于100 ppm甲醛气体有着20的灵敏度,检测下限可达5 ppm,响应恢复时间在5 s之内,而且对甲醛气体有着很好的选择性。并解释了Ag掺杂改善气敏性能的机理。第三,通过水热法来合成SnO_2八面体材料,并在表面修饰贵金属Au,制备出AuSnO_2八面体材料,通过表征手段证明Au成功的修饰在SnO_2八面体材料表面,并且测试了Au-SnO_2八面体材料的乙炔气敏性能。纯的SnO_2八面体材料区分乙炔气体的能力并不好,而利用Au粒子的表面修饰之后,对于乙炔气体的响应度和选择性明显提高。Au修饰SnO_2八面体材料对于100 ppm乙炔气体有着33的响应,检测下限可低达1ppm,而且极大的降低了器件的工作温度,展现出了良好的乙炔气敏性能。
[Abstract]:With the development of society and the progress of science and technology, people pay more and more attention to quality of life. It is inevitable to encounter some poisonous, flammable and explosive gases in daily life, which will cause harm to personal and property. At this point, the gas sensor will play a very important role, it can timely detect the gas atmosphere in the environment. Today, researchers are working on high performance, fast response recovery and high selectivity gas sensors. Among many gas sensors, metal oxide semiconductor gas sensor is one of the most important gas sensors. It has the advantages of simple preparation process, low cost and good gas sensitivity. At present, people try different methods to synthesize oxide semiconductor materials. However, the application of pure oxide semiconductors in gas sensors has some shortcomings, such as low sensitivity, slow response recovery, poor selectivity and so on. In this way, the performance of metal oxide semiconductor gas sensor is improved from the aspects of material morphology, doping, surface modification and material recombination. In order to improve the gas sensitivity of the materials, the surface modification or doping of metal oxide semiconductors with precious metals was carried out, and the corresponding gas sensors were prepared. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray fluorescence spectroscopy (EDX) were used to analyze the composition and morphology of the materials. This thesis mainly includes the following three parts: first, the SnO-2) nanofibers were synthesized by electrospinning. The SnO_2 nanofibers and Au-SnO_2 nanofibers were modified by wet modification method, and the formaldehyde gas sensing properties were tested. Compared with SnO_2 nanofiber material, the responsivity of Au-SnO2 is increased by 2 times, and the working temperature is lower and the selectivity is better. Secondly, lanthanum ferrate (LaFeO3) nanofibers doped with different noble metal Ag (Ag) content were prepared by electrospinning method, and the formaldehyde gas sensing properties of the materials were compared to find out the best Ag doping ratio to improve the gas sensitivity. The LaFeO_3 nanofibers doped with noble metal Ag have better formaldehyde gas sensing properties, and the 2 mol%Ag doped LaFeO_3 nanofibers have the best gas sensing properties. At this time, the sensitivity of 100 ppm formaldehyde gas is 20, the detection limit is up to 5 ppm, the response recovery time is less than 5 seconds, and the selectivity of formaldehyde gas is very good. The mechanism of Ag doping to improve gas sensitivity is also explained. Thirdly, the SnO_2 octahedron material was synthesized by hydrothermal method. The AuSnO_2 octahedron material was prepared by modifying the surface of the noble metal Au. the au was successfully modified on the surface of the SnO_2 octahedron material by means of characterization. The acetylene gas sensing properties of Au-SnO_2 octahedral materials were also tested. The ability of pure SnO_2 octahedron material to distinguish acetylene gas is not good, but after surface modification of au particles, the responsivity and selectivity of SnO_2 octahedron modified with au particles to acetylene gas increase obviously, and the SnO_2 octahedron material modified by au has 33 response to 100 ppm acetylene gas. The detection limit can be as low as 1 ppm, and greatly reduces the operating temperature of the device, showing good acetylene gas sensitivity.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304;TP212

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