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A parametric study of gas sensing response of zinc oxide nanostructures and carbon nanotubes.

机译：氧化锌纳米结构和碳纳米管气体传感响应的参数研究。

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摘要

In this work, ZnO nano-structures and carbon nanotubes (CNTs) have been tested as chemical sensors and a detailed study on the effect of different process parameters such as temperature, carrier gas flow, inter-electrode spacing, gas concentration and material properties on gas sensitivity is presented.;Initial ZnO nanoparticles were prepared by a simple solution chemical process and characterized by Secondary Electron Microscopy (SEM) and Brunauer, Emmet and Teller (BET) Sorptometer to demonstrate the morphology and surface area respectively. The gas sensor platforms consisted of Pt inter-digitated fingers with a spacing of 10 &mgr;m. The sensor platform was dip-coated with ZnO nano-platelets suspended in terpineol to form a uniform film. Sensing was performed in a closed quartz chamber where, high purity N2 and dry industrial air were used as carrier and recovery gas respectively. Sensitivity of nano-platelets and porous films was measured for different concentrations of the analyte (H2). High response was observed at room temperature for H2 gas with sensitivities in excess 80% for 60ppm and about 55% for 80ppm of H2 gas at room temperature was observed for the nano-platelets and the porous films respectively. High sensitivity of the sensor at low temperatures is attributed to both the increased surface area of the porous ZnO nano-platelets and the presence of a Pt catalyst. Measurements at higher temperatures (150 °C) show even higher sensitivities, near 96% for a 20 ppm H2 concentration. Sensitivity with different gases and organic solvents was also measured at operating temperatures of 200°C. Values on the order of 60%, 42% and 29% for 315 PPM of CO, O 2 and NH3 whereas sensitivity values of 77.76%, 70.26% and 38.43% for C2H5OH, CH3OH and H2O were recorded for concentration values approximating 500 PPM. The sensors depict incomplete recovery of resistance at room temperature. This effect is possibly due to the traces of elemental Zn in the material, which were not oxidized at the time of recovery. However, this effect was not observed at higher temperatures.;Designed experiments conducted to understand effects of various device and process parameters show negative dependence of spacing on sensitivity with maximum effect of applied bias for lower concentration values. The sensitivity of the sensor was also recorded to increase with the increase in the number of electrodes. Higher sensitivity values nearing 70% were achieved with 30 IDEs for 60 PPM H2 when compared to 60% for 60 PPM of H2 with 20 IDEs. Interaction effects were observed and implemented to understand and model the behavior of the gas sensor.;Sensitivity of arc produced CNTs was measured to various gases and organic solvents. Values on the order of 24% were observed at 80 PPM CO as compared to values of sensitivity about 15% for O2 and 3% for H2. Also, sensitivity value of 15% was measured for as low as 4 PPM of DMA which suggests the capability of PPB levels of DMA using CNTs. A brief comparison of sensitivity values achieved for ZnO nano-platelets and CNTs with similar analytes was also presented.;Sensitivity to different analytes was measured using impedance spectroscopy for HiPCo produced SWCNT network. For experiments conducted with varying exposure time, sensitivity values nearing 6% for 0.01% (100 PPM) DMA for an exposure time of 25 minutes were recorded. Sensitivity values recorded for other solvents were 16.74%, 10.98%, 7.97%, 6.96% and 4.28% for concentration levels of 2.04%, 4.02%, 2.04%, 14% and 6.05% of NH3, IPA, CO, CH3OH and C2H5OH respectively. For experiments with varying concentration values of different analytes, higher response was observed for gaseous analytes. Results on the order of 15.27% and 3.82% were recorded for as low as 0.18% of both NH3 and CO. For the organic solvents, values approximating 2.64%, 2.36% and 0.10% for concentration levels of 0.29%, 0.92% and 0.42% of IPA, CH3OH and C2H5OH respectively. Results obtained with HiPCo produced SWCNT network at room temperature were comparable to the values of sensitivity shown by other researchers. (Abstract shortened by UMI.)
机译：在这项工作中，已经测试了ZnO纳米结构和碳纳米管（CNT）作为化学传感器，并详细研究了不同工艺参数（例如温度，载气流量，电极间间距，气体浓度和材料特性）的影响。通过简单的溶液化学方法制备了初始ZnO纳米粒子，并通过二次电子显微镜（SEM）以及Brunauer，Emmet和Teller（BET）溶出度计进行了表征，以分别证明其形貌和表面积。气体传感器平台由间距为10μm的Pt叉指组成。传感器平台浸有悬浮在松油醇中的ZnO纳米血小板，以形成均匀的膜。传感在封闭的石英室中进行，在石英室中，高纯度N2和干燥的工业空气分别用作载气和回收气。测量了不同浓度的分析物（H2）的纳米片和多孔膜的灵敏度。在室温下观察到H 2气体的高响应，对于纳米片和多孔膜，分别在60ppm和80ppm H 2气体下的灵敏度超过80％，在室温下分别观察到约55％的H 2气体。传感器在低温下的高灵敏度归因于多孔ZnO纳米片表面积的增加和Pt催化剂的存在。在较高温度（150°C）下进行的测量显示出更高的灵敏度，对于20 ppm H2浓度，灵敏度接近96％。还在200°C的工作温度下测量了不同气体和有机溶剂的灵敏度。对于浓度为500 PPM的C2H5OH，CH3OH和H2O，对于315 PPM的CO，O 2和NH3值分别为60％，42％和29％，而灵敏度值分别为77.76％，70.26％和38.43％。传感器显示了室温下电阻的不完全恢复。这种影响可能是由于材料中的微量锌元素，在回收时并未被氧化。但是，在较高温度下未观察到此效应。为了了解各种器件和工艺参数的影响而进行的设计实验显示，间距对灵敏度具有负相关性，对于较低的浓度值，施加的偏置效应最大。还记录了传感器的灵敏度随着电极数量的增加而增加。 30个IDE的60 PPM H2达到了接近70％的更高灵敏度值，而20个IDE的60 PPM的H2达到了60％的灵敏度值。观察并实现了相互作用效应，以理解和建模气体传感器的行为。；测量了电弧产生的CNT对各种气体和有机溶剂的敏感性。在80 PPM CO下观察到的数值约为24％，而O2的灵敏度约为15％，H2的灵敏度约为3％。同样，对于低至4 PPM的DMA，测量的敏感度值为15％，这表明使用CNT的DMA的PPB水平。还简要介绍了使用相似分析物的ZnO纳米血小板和CNT的灵敏度值的比较。；使用阻抗光谱法对HiPCo生产的SWCNT网络测量了对不同分析物的灵敏度。对于在不同曝光时间下进行的实验，记录25分钟曝光时间下0.01％（100 PPM）DMA的灵敏度值接近6％。对于浓度分别为NH3，IPA，CO，CH3OH和C2H5OH的2.04％，4.02％，2.04％，14％和6.05％的浓度，其他溶剂的灵敏度值分别为16.74％，10.98％，7.97％，6.96％和4.28％。 。对于不同分析物浓度值变化的实验，观察到气态分析物的响应更高。 NH3和CO含量低至0.18％时，记录的结果分别为15.27％和3.82％。对于有机溶剂，浓度水平为0.29％，0.92％和0.42时，值分别约为2.64％，2.36％和0.10％。分别为IPA，CH3OH和C2H5OH的％。用HiPCo产生的SWCNT网络在室温下获得的结果与其他研究人员显示的灵敏度值相当。 （摘要由UMI缩短。）

著录项

  • 作者

    Saluja, Amandeep S.;

  • 作者单位

    Rochester Institute of Technology.;

  • 授予单位 Rochester Institute of Technology.;
  • 学科 Statistics.;Engineering Materials Science.
  • 学位 M.S.
  • 年度 2009
  • 页码 120 p.
  • 总页数 120
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 统计学;工程材料学;
  • 关键词

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