氧化锌纳米结构缺陷控制与气敏性能关系研究

发布时间：2018-01-05 11:06

本文关键词：氧化锌纳米结构缺陷控制与气敏性能关系研究　出处：《天津理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：ZnO是一种宽禁带的金属氧化物半导体,因其独特的电学和光学性质,在气敏传感、光催化和废水处理等领域都有非常广泛的应用。因为ZnO形貌丰富、成本低廉、无毒无害、绿色环保等优点,在气敏传感方向的应用备受瞩目。ZnO属于表面电阻控制型半导体,气敏响应主要取决于表面结构,所以具有大的比表面积的片状结构和有助于气体扩散的多孔空心结构均有利于提高气敏性能。此外,考虑到氧化石墨烯(GO)特殊的运输特性和极高的载流子迁移率,其与ZnO的复合材料也能表现出优良的气敏性能。本论文主要研究内容如下:1)在没有任何模板、表面活性剂或有机溶剂的情况下,采用直接沉淀的方法在室温下合成了平均厚度约为20 nm的氧化锌(ZnO)纳米片。为了提高热稳定性、调控表面本征缺陷含量,将样品分别在200°C、400°C和600°C下煅烧,结果表明,片状结构可以在低于400°C下稳定存在。光致发光谱(PL)分析显示,ZnO-200样品表面上存在大量的本征缺陷;气敏测试表明,由ZnO-200纳米片制作的气体传感器在300°C下对丙酮显示出较高的气敏响应和良好的选择性。因此,我们认为ZnO-200对丙酮显示的灵敏度的增强,除了比表面积的影响外,主要起因于材料表面的本征缺陷。2)通过一种简单有效、低碳环保的水浴法制备了不同氧化石墨烯含量的石墨烯/ZnO的复合体系,随后制成气敏器件,对其气敏性能进行测试。结果表明,掺杂0.5 mg氧化石墨烯的ZnO复合材料(ZnO-0.5 GO)在200°C下对二甲胺显示出良好的气敏性能。结果表明,0.5 mg氧化石墨烯为最佳复合含量,并在复合过程中通过原位C掺杂形成了一些施主型杂质缺陷,主要是CZn和Ci,这些均有利于吸附氧的增加,从而提升灵敏度,其在200°C下对1 ppm二甲胺的灵敏度可高达4.82。我们还发现GO/ZnO复合材料在低工作温度下的n-p转换主要是吸附抑制载流子传输引起的,而低二甲胺浓度下的n-p转换是由于对于p型半导体而言,空穴浓度的降低比电子浓度的增加更为重要。3)以葡萄糖和氯化锌为原料,采用两步法(一步水热、二步煅烧)以碳球为模板在不同煅烧温度下牺牲模板合成了ZnO空心微球结构,同时也实现了碳的原位掺杂。气敏性能测试表明,在600°C下煅烧的的空心微球(ZnO-600)在最佳工作温度(240°C)下对二甲胺显示出了最佳的气敏性能,尤其是对1 ppm的二甲胺灵敏度可达7.21,在低浓度二甲胺检测领域有良好的应用前景。通过研究讨论发现优良的气敏性能是材料的比表面积和表面缺陷共同作用所致。
[Abstract]:ZnO is a wide band gap metal oxide semiconductor, because of its unique electrical and optical properties in gas sensing, photocatalytic wastewater treatment and other fields have a very wide application. Because the morphology of ZnO rich, low cost, non-toxic harmless, green environmental protection and other advantages, the application in gas sensing the direction of attention.ZnO belongs to control type semiconductor surface resistance, gas sensing response mainly depends on the surface structure, so it has large specific surface area and the lamellar structure of porous hollow structure is helpful to the gas diffusion to improve gas sensing properties. In addition, considering graphene oxide (GO) carrier transport characteristic and high special migration rate of composite materials with ZnO can exhibit excellent gas sensing properties. The main research contents of this paper are as follows: 1) in the absence of any templates, surfactants or organic solvent, by direct precipitation Methods was synthesized at room temperature with an average thickness of about 20 nm Zinc Oxide (ZnO) nano film. In order to improve the thermal stability of the intrinsic defects in the regulation of surface, the samples were at 200 ~ C, 400 ~ C and 600 ~ C under calcination, results show that the sheet structure can be lower than 400 DEG C under stable deposit in the photoluminescence spectra (PL) analysis showed that the existence of intrinsic defects on the surface of a large number of ZnO-200 samples; gas sensing tests show that the nano ZnO-200 gas sensor fabricated in 300 ~ C of acetone showed higher response sensitivity and good selectivity. Therefore, we believe that ZnO-200 enhanced sensitivity to acetone the show, in addition to the effect of surface area, mainly because of the intrinsic defects on the surface of the.2) by a simple and effective, composites of graphene /ZnO different graphene oxide content in the preparation of low carbon environmental protection water bath method, then made of gas sensors, the The gas sensing properties were tested. The results show that the ZnO composite 0.5 mg doped graphene oxide (ZnO-0.5 GO) at 200 DEG C to two methylamine showed good gas sensing properties. The results showed that the optimum content is 0.5 mg graphene oxide, and the composite process by in situ C doped form some donor impurity defects, mainly CZn and Ci, which are conducive to the increase of adsorbed oxygen, so as to enhance its sensitivity at 200 ~ C sensitivity of 1 ppm two methylamine can be as high as 4.82. we found that N-P conversion GO/ZnO composites at low working temperature is mainly caused by the inhibition of adsorption carrier transport. N-P two the conversion of low concentration of methylamine is due to p type semiconductor, reduce the hole concentration than the electron concentration is more important.3) with glucose and zinc chloride as raw material by two step (step two step hydrothermal calcination) with carbon spheres as The template in different temperatures sacrificial template ZnO hollow microspheres were synthesized, but also realize the in situ doped carbon. Gas sensitivity tests show that the hollow microspheres calcined at 600 ~ C (ZnO-600) at the optimal temperature (240 degrees C) to two methylamine showed the best sensing properties especially, two of the 1 ppm methylamine sensitivity of 7.21, a good prospect in the field of low concentration of two methylamine detection. Through the research and discussion found excellent gas sensitivity property are material specific surface area and surface defects caused by joint action.

【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ132.41;TB383.1

【相似文献】