秸秆分级结构金属氧化物的制备及其气敏性能研究

发布时间：2018-04-12 11:31

  本文选题：生物模板 + 秸秆　； 参考：《吉林大学》2017年硕士论文

【摘要】：面对环境污染治理、工业生产安全以及日常生活健康等多方面的需求,开发出灵敏度高、响应速度快、稳定性高的气体传感器是目前亟须解决的问题。在各类传感器中,金属氧化物气体传感器由于成本低廉、工艺灵活性大、使用方法简单、可探测气体种类多等优点引起广泛关注。近年来,利用生物模板法合成多级精细复杂结构的新型功能材料是新兴研究方向。因此,选择获取简单、数量庞大和绿色环保的生物模板制备金属氧化物半导体气敏传感器具有重要的研究价值。本研究利用玉米秸秆的天然分级多孔结构,采用液相浸渍、焙烧的工艺,成功制备得到秸秆分级结构ZnO材料,并对材料进行物相组成、形貌结构以及孔结构分析,并研究了其气敏性能,分析了秸秆分级多孔结构对ZnO气敏性能的影响。在秸秆分级结构ZnO的基础上,利用过渡金属离子掺杂改性手段改善ZnO气敏性能,为分级多孔结构材料的组分优化方面提供依据。本研究主要结果如下:(1)采用玉米秸秆为模板,经过原料氨水抽提预处理、二次浸渍、焙烧去模板等工序,成功制备得到具有秸秆分级多孔结构的ZnO材料。对样品进行表征,ZnO材料很好地复制保留了秸秆的分级多孔结构,而且其分级结构是由大约50nm的纳米颗粒构成的。该样品同时具有分级大孔和不对称的细长介孔,样品比表面积为32.84 m2/g,平均孔径为18.9 nm,孔容为0.16 m3/g。(2)气敏测试发现,秸秆分级结构ZnO对丙酮的灵敏度比常规ZnO高,但其最佳工作温度也高于常规ZnO,这可能是因为秸秆分级结构ZnO材料的表面活性不足,需要高的工作温度也就是更高的表面反应激活能才可以发挥其气敏性能。秸秆分级结构ZnO在340℃最佳工作温度下对100 ppm丙酮的灵敏度可达~24,响应和恢复时间分别为12 s和6 s。秸秆分级多孔ZnO的特殊结构在不同尺度上为气体在材料内部快速扩散传输提供了大量的通道,而且不论在微米尺度上还是纳米尺度上均具有大的比表面积,这将为表面反应提供更多的活性位点,从而增强材料的气敏性能。(3)采用过渡金属离子掺杂及秸秆分级多孔ZnO的结构优势相结合的方法,选用Ni作掺杂剂,制备得到了具有秸秆分级多孔结构的Ni掺杂ZnO材料,大大改善了ZnO的气敏性能。在340℃工作温度下,ZnO:Ni元件对100 ppm丙酮的灵敏度可达~68,响应和恢复时间分别仅为6 s和2 s,理论检测限为116 ppb,该元件具有好的选择性及长期稳定性。气敏性能优于纯ZnO可能是因为Ni掺杂ZnO材料相较于纯ZnO具有更高的施主缺陷含量。
[Abstract]:Facing the demands of environmental pollution control, industrial production safety and daily life health, it is urgent to develop gas sensors with high sensitivity, fast response and high stability.In recent years, it is a new research direction to synthesize new functional materials with multilevel fine and complex structure by biological template method.Therefore, the preparation of metal oxide semiconductor gas sensors with simple, large number and green biological templates has important research value.In this study, the natural porous structure of corn straw was used to prepare the ZnO material by liquid phase impregnation and roasting, and the phase composition, morphology and pore structure of the material were analyzed.The gas sensing properties of ZnO were studied, and the effect of porous structure of straw classification on gas sensing performance of ZnO was analyzed.On the basis of ZnO of straw grading structure, the gas sensing properties of ZnO were improved by using transition metal ion doping modification method, which provided the basis for the composition optimization of graded porous structure materials.The main results are as follows: (1) using corn straw as template, ZnO material with straw grading porous structure was successfully prepared by pretreatment with ammonia water extraction, secondary impregnation, roasting and deformation.The sample was characterized by 50nm, which was made up of about 50nm nanoparticles, and retained the porous structure of the straw.However, the optimum operating temperature is also higher than that of conventional ZnO, which may be due to the lack of surface activity of straw fractionated ZnO, which requires a higher working temperature, that is, a higher surface reaction activation energy to give full play to its gas-sensing properties.The sensitivity of straw grading structure ZnO to 100 ppm acetone at 340 鈩，

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