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Research On Gas Sensing Properties Of Nanostructure Composed Of Carbon Nanotubes Doped With Metal Oxide Nanopowder

Posted on:2017-04-22Degree:MasterType:Thesis
Country:ChinaCandidate:J H FangFull Text:PDF
GTID:2308330485489316Subject:Instrumentation engineering
Abstract/Summary:PDF Full Text Request
Nowadays, with the rapid development of science and technology, more and more environmental problems appear in front of people. The frequency of haze, overproof formaldehyde in decoration materials and accidental leakage of chemical raw materials have seriously endangered people’s health, which put forward the requirement for the high efficiency and accuracy of the gas sensor. But many sensors have a series of problems, such as higher operating temperature, slower response speed and lower sensitivity. In view of these problems, the preparation and design of the gas sensor with high sensitivity and low operating temperature is realized by doping the carbon nanotubes in metal oxide. The main contents were as follows:(1) The preparation method of heater-type gas sensor was selected through studying the preparation technology and principle of gas sensor. Carbon nanotubes were treated by chemical modification and the materials were characterized by scanning electron microscopy and X-ray powder diffraction. The results showed that the treated carbon nanotubes strengthened the adsorption ability of the gas and the doping ability, which provided the theoretical basis for the following experiments.(2) Nano Fe2O3 particles were prepared by precipitation method and composited with carbon nanotubes, the effect of different sintering temperature on the gas sensitivity of the sensor was studied. The influence of doping amount, working temperature and gas concentration on the sensitivity of the sensor was emphatically analyzed, meanwhile do research on sensing mechanism. The results showed that the sensitivity of CNT/Fe2O3 sensor to acetone was improved greatly and reduced the working temperature of the sensor. Various performance indexes about Fe2O3 gas sensor were improved, especially the sensitivity of the 80 ppm acetone atmosphere reached 2.3.(3) In order to further verify the effective improvement of the gas sensing properties of the doped carbon nanotubes in the nano metal oxide, SnO2 and In2O3 nanoparticles were prepared by using a sol-gel method and then doped with carbon nanotubes, its gas sensing properties were studied. The results showed that when the doping amount was 5%, the sensitivity of CNT/SnO2 was 3.5 times that of pure SnO2, and when the doping amount was 3%, the sensitivity of CNT/In2O3 was 2 times that of pure In2O3. Two kinds of gas sensors not only reduced the working temperature, but also shortened the response time. Among them, CNT/SnO2 had good selectivity to formaldehyde and CNT/In2O3 had good selectivity to ethanol.
Keywords/Search Tags:carbon nanotubes, metal oxide, nano structure, gas sensitivity
PDF Full Text Request
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