复合及掺杂对NiO纳米材料的甲苯、二甲苯气敏性能改进的研究

发布时间：2018-05-09 19:37

本文选题：氧化镍 + Cr掺杂　；参考：《吉林大学》2015年硕士论文

【摘要】：如今，科技高速发展，人们的生活水平快速提高的同时，各种各样的问题越来越被人们所关注。其中空气污染问题越来越严重，易燃易爆气体和有毒有害气体无时不刻地危害着人们的身体健康。因此，如何有效地监测和检测环境中易燃易爆和毒有害气体就成为重要问题。在气体传感器中，金属氧化物型半导体式气体传感器性能优良、成本低廉。在本文中选择氧化镍半导体材料为基体材料。但是由于纯半导体金属氧化物材料的灵敏度不够高，选择性也较差。因此我们对氧化镍半导体材料进行了改性。在本文中，主要采取两个方面对氧化镍材料的气敏性能进行改善：首先，利用半导体复合技术改善氧化镍材料气敏性能；其次，利用原位掺杂技术对氧化镍材料进行改性。具体如下：通过水热法合成NiO空心材料。利用XRD、SEM、BET等表征手段对合成材料下进行了系统的表征。并将合成的NiO空心材料制备成气体传感器并进行了气敏性能测试。结果表明，，空心结构的NiO材料制备的气体传感器有良好的敏感性能。NiO空心结构纳米材料基气体传感器对甲苯、二甲苯有最高的响应度，说明NiO空心结构纳米材料有成为优异甲苯、二甲苯气体传感器的潜力。利用半导体复合技术对NiO材料进行改性。通过水热法合成Fe3O4-NiO核壳结构复合材料。Fe3O4的复合明显提高了NiO传感器对甲苯及二甲苯气体的灵敏度和选择性。在Fe3O4-NiO复合材料最佳工作温度280oC下，复合后的传感器对100ppm甲苯的灵敏度约为复合前的3倍。选择性在复合后也有一定的提高。传感器在复合后对甲苯气体传感性能提升主要原因可能是异质结的势垒高度在目标气体和空气中的变化。针对NiO气体传感器选择性较差的问题，利用原位掺杂的技术对NiO材料进行改性，可以很好地解决这一问题。首先利用水热法合成Cr掺杂NiO材料并制作成气体传感器，研究了Cr掺入量对传感器性能的影响。结果表明Cr掺杂使得器件的最佳工作温度有明显的升高，并且掺杂浓度为2at%的Cr-NiO纳米材料对二甲苯有最高的响应度。除此之外，Cr掺杂后的NiO气体传感器的选择性能有非常明显的提高。Cr掺杂后的NiO气体传感器对二甲苯、甲苯的灵敏度提高的原因主要由两个方面。首先是Cr的掺杂导致表面氧空位增加，提升了表面氧化能力。其次是Cr3+或Cr2O3在器件最佳工作温度下对甲基有非常好的催化效应。器件选择性的提高也主要归因与Cr3+或Cr2O3的催化效应。
[Abstract]:Nowadays, with the rapid development of science and technology and the rapid improvement of people's living standard, people pay more and more attention to all kinds of problems. Among them, air pollution is becoming more and more serious, flammable and explosive gases and poisonous and harmful gases are harming people's health all the time. Therefore, how to effectively monitor and detect flammable, explosive and toxic gases in the environment has become an important issue. In gas sensor, metal oxide semiconductor gas sensor has good performance and low cost. In this paper, the nickel oxide semiconductor material is selected as the substrate material. However, the sensitivity and selectivity of pure semiconductor metal oxide materials are not high enough. Therefore, we modified the nickel oxide semiconductor material. In this paper, the gas sensing properties of nickel oxide materials were improved in two aspects: firstly, the semiconductor composite technology was used to improve the gas sensing properties of nickel oxide materials; secondly, in situ doping technology was used to modify nickel oxide materials. The details are as follows: NiO hollow materials were synthesized by hydrothermal method. The synthetic materials were systematically characterized by XRDX SEMX BET and so on. The NiO hollow material was prepared into a gas sensor and its gas sensing performance was tested. The results show that the gas sensor prepared by hollow structure NiO material has good sensitivity. Nio hollow structure nano-material gas sensor has the highest responsivity to toluene and xylene. The results show that NiO hollow nanostructure has the potential to be an excellent gas sensor for toluene and xylene. NiO materials were modified by semiconductor composite technology. The composite of Fe3O4-NiO core-shell structure composite 路Fe _ 3O _ 4 was synthesized by hydrothermal method. The sensitivity and selectivity of NiO sensor to toluene and xylene gas were improved obviously. The sensitivity of the composite sensor to 100ppm toluene is about three times as high as that of the former at the optimum working temperature of Fe3O4-NiO composite 280oC. The selectivity is also improved after recombination. The main reason for the improvement of the performance of the sensor is the variation of the barrier height of the heterojunction in the target gas and the air. In order to solve the problem of poor selectivity of NiO gas sensor, in situ doping technology can be used to modify NiO materials. Firstly, the Cr doped NiO material was synthesized by hydrothermal method and the gas sensor was fabricated. The effect of Cr content on the performance of the sensor was studied. The results show that Cr doping can obviously increase the optimal operating temperature of the device, and the Cr-NiO nanocrystalline with doping concentration of 2 at% has the highest responsivity to xylene. In addition, the selective performance of Cr doped NiO gas sensor is obviously improved. The main reasons for the increase of sensitivity of NiO gas sensor after Cr doping are two aspects. Firstly, the doping of Cr leads to the increase of oxygen vacancy on the surface, which improves the oxidation ability of the surface. Secondly, Cr3 or Cr2O3 have very good catalytic effect on methyl at the optimum operating temperature. The improvement of device selectivity is also attributed to the catalytic effect of Cr3 or Cr2O3.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.2;TB383.1

【参考文献】