导电高分子复合材料的制备及其低温气敏性能研究

发布时间：2018-01-15 01:01

本文关键词：导电高分子复合材料的制备及其低温气敏性能研究　出处：《郑州大学》2017年博士论文　论文类型：学位论文

【摘要】：气敏材料的性能决定着气敏元件及其气体传感器的性能。针对目前气敏材料在使用过程中存在的问题,为进一步提高其低温气敏性能,结合导电高分子材料、石墨烯及金属氧化物的各自特性,本文系统研究了导电高分子复合材料的制备及其低温气敏性能。其主要内容如下:1.将具有室温气敏性的导电高分子材料与比表面积较大、电子转移能力较强的石墨烯相结合,通过原位化学氧化聚合法制备出了一种二元复合气敏材料聚噻吩/石墨烯(PTh/rGO),并对其结构和气敏性能进行了表征和测试分析。结果表明该复合材料在室温下对NO_2的灵敏度和选择性均优于单一聚噻吩。2.金属氧化物半导体气敏材料的缺点是操作温度高(250-600℃),但其灵敏度、稳定性和响应恢复性能较好。为了进一步提高导电高分子材料的低温气敏性能,将上述二元复合气敏材料与相关金属氧化物相结合,研究合成出了两种三元导电高分子复合材料:聚噻吩/石墨烯/WO_3(PTh/rGO/WO_3)和聚吡咯/石墨烯/In_2O_3(PPy/rGO/In_2O_3)。研究过程中,首先利用水热法合成出了两种二元材料rGO/WO_3和r GO/In_2O_3,进而采用化学氧化聚合法分别制备出了PTh/rGO/WO_3和PPy/r GO/In_2O_3两种三元复合材料,并采用场发射扫描电镜、透射电镜、比表面积分析仪、红外光谱仪、X射线衍射仪等手段对其结构和形貌进行了表征,同时,还利用气敏测试设备对其低温气敏性能进行了测试。结果表明工作温度在75℃或室温下,其灵敏度、选择性和响应恢复性能均优于二元复合材料。3.为了提高三元复合材料的稳定性,本文在含有还原态金属氧化物TiO_2和氧化石墨烯(GO)之间引入酰胺键,合成出TiO_2/GO后,再利用化学氧化聚合法将TiO_2/GO与导电高分子材料聚苯胺(PANI)进行结合,从而成功合成出了三元复合材料PANI/TiO_2/GO,通过相关表征和测试手段,不仅说明三元复合材料中存在酰胺键,进一步提高了材料的稳定性,而且,室温下对NH_3的灵敏度、选择性及其元件的恢复性能均有所提高,是一种较佳的导电高分子三元复合气敏材料。4.本文还探讨了导电高分子材料与金属氧化物半导体材料复合后在紫外光激发下的低温气敏性能,首先分别合成出了两种中间体Zn_5(CO_3)_2(OH)_6纳米片和ZnO_2,然后通过在400℃下煅烧分别得到ZnO纳米片和富含氧空位缺陷的ZnO,再利用化学氧化聚合法分别与PANI和PTh结合,最后得到两种导电高分子与金属氧化物结合的二元复合材料PANI/ZnO和PTh/ZnO,同时对所制备的二种二元复合材料分别进行了结构表征和气敏性能测试。结果发现在紫外光激发下,两种材料对乙醇气体均具有较好的灵敏度和响应与恢复性能,且稳定性较好。在无紫外光照射时,二者对乙醇均没有气敏性,原因在于在紫外光照射下,有机与无机材料之间存在着电荷转移的协同效应。5.本文还对所合成复合材料的气敏机理进行了分析。导电高分子材料(PANI、PTh、PPy)具有室温气敏性能,可降低气敏材料的操作温度;金属氧化物半导体材料的稳定性好、灵敏度高、响应和恢复时间短;石墨烯具有较大的比表面积和优良的电子转移能力,将三者进行复合后,很好地发挥了三者之间的协同效应。具体可归纳为三点:第一、大的比表面积为表面化学反应提供了充足的活性位点,同时有利于气体的快速扩散;第二、金属氧化物与石墨烯之间存在着电子转移作用;第三、金属氧化物(n型半导体)与导电高分子材料和石墨烯(p型半导体)之间可形成p-n异质结,通过异质结也可产生电子转移,从而表现出低温下复合材料的较佳气敏性能。
[Abstract]:The properties of gas sensitive materials determines the performance of gas sensor and gas sensor. According to the existing in the process of using gas sensitive materials at present, to further improve the low temperature gas sensing properties, combined with conductive polymer materials, their properties of graphene and metal oxides, this paper investigated the preparation of conductive polymer composites low temperature and gas sensing properties. The main contents are as follows: 1. conductive polymer materials will have room temperature of gas with large specific surface area, strong ability of electron transfer of graphene was prepared by combining a two element composite gas sensitive material polythiophene / graphene by in situ chemical oxidation polymerization (PTh/rGO). Then the structure and gas sensing properties were characterized and analyzed. The results show that the composite material at room temperature on NO_2 sensitivity and selectivity than single polythiophene.2. metal oxide semiconductor Gas sensitive materials is high operating temperature (250-600 degrees), but its sensitivity, stability and response performance. In order to further improve the low temperature gas sensitive properties of conductive polymer materials, the two element composite metal oxide gas sensitive materials and combining research, synthesis of two yuan of three kinds of conductive polymer composite material: polythiophene / graphene /WO_3 (PTh/rGO/WO_3) and Polypyrrole / graphene /In_2O_3 (PPy/rGO/In_2O_3). The course of the study, first by hydrothermal synthesis of two yuan of two kinds of materials of rGO/WO_3 and R GO/In_2O_3, which were prepared with PTh/rGO/WO_3 and PPy/r two GO/In_2O_3 three composite materials by chemical oxidation polymerization method, and by field emission scanning electron microscopy, transmission electron microscopy, surface area analyzer, infrared spectrometer, the structure and morphology were characterized by X ray diffraction method at the same time, using the gas sensing The test equipment for the test of the low temperature gas sensing properties. The results show that the temperature of 75 DEG C or at room temperature, the sensitivity, selectivity and response recovery properties were better than the two.3. composites in order to improve the stability of three element composite material, this paper contains reducible metal oxide TiO_2 and graphene oxide (GO). The introduction of amide bonds, synthesized by TiO_2/GO, and then the chemical oxidative polymerization of TiO_2/GO and conductive polymer polyaniline (PANI) were combined to successfully synthesize three PANI/TiO_2/GO composites, through characterization and testing means, not only shows the presence of amide bonds three yuan in composite materials, to further improve the stability of materials moreover, the sensitivity of NH_3, room temperature, selectivity and element recovery performance were improved, is a kind of conductive polymer better three element composite gas sensitive material.4. in this paper The conductive polymer materials and metal oxide semiconductor composites under ultraviolet excitation at low temperature on gas sensing properties, were first synthesized two kinds of intermediate Zn_5 (CO_3) _2 (OH) _6 nanosheets and ZnO_2, and then was annealed at 400 were ZnO nanoplates and rich oxygen vacancies in ZnO. And then the chemical oxidative polymerization were combined with PANI and PTh, and finally get the two kinds of conductive polymer and metal oxide with the two element composite materials of PANI/ZnO and PTh/ZnO at the same time, the preparation of the two two yuan composite were characterized and the gas sensing performance test. The results showed that under the excitation of UV light, two kinds of materials have good sensitivity and response and recovery performance of ethanol gas, and better stability. In the absence of UV irradiation, the two are not gas sensitivity to alcohol, the reason lies in the UV light irradiation, Between organic and inorganic material have a synergistic effect of.5. charge transfer in this paper also analyzes the gas sensing mechanism of the synthesized composites. Conductive polymer materials (PANI, PTh, PPy) with room temperature sensing performance, can reduce the operating temperature of gas sensitive material; metal oxide semiconductor material has good stability, high sensitivity. Short response and recovery time; graphene has the specific surface area and excellent electron transfer capacity is large, the three compound, played a good synergistic effect between the three. The specific can be summarized in three points: first, the active site provides sufficient surface area for surface chemical reaction at the same time, favors the fast diffusion of gases; second, between the metal oxide and graphene has effect of electron transfer; third, metal oxides (n type semiconductor) and conductive polymer materials and Shi Moxi (P type semiconductor). The p-n heterojunction can be formed between the heterojunction and the electron transfer can be produced by the heterojunction, which shows the better gas sensitivity of the composite at low temperature.

【学位授予单位】：郑州大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB381

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