研究目的
To design gas sensor detectors based on single-walled carbon nanotubes (SWCNTs) with high sensitivity and selectivity for the toxic environment, specifically to detect NO2 gas with better sensitivity.
研究成果
We have developed a chemiresistive SWCNTs-PEI functionalized gas sensor by using a thermal CVD method. The higher adhesive coefficient for the electron-withdrawing NO2 of PEI-coated SWCNTs than untreated SWCNTs. At room temperature, PEI-SWCNTs-coated resistive gas sensor demonstrated elevated sensing behaviour and swift reaction to NO2. Furthermore, owing to room temperature operation of the resistive gas sensor can be encouragingly exploited in the environment observation.
研究不足
The major challenge faced was the recovery of the sensor. The fast recovery was accomplished by the use of UV illumination. The influence of moisture on the actual gas sensing response is found to be insignificant.
1：Experimental Design and Method Selection:
The SWCNTs sensor was grown by using the standard thermal CVD method. The SWCNTs films were deposited on a SiO2/Si substrate by using standard thermal chemical vapour deposition (CVD) method and co-sputtering was used for preparing the catalyst. The two planer Au electrodes were deposited on the as-grown SWCNTs surface by sputtering method followed by patterning with the standard lift-off method.
2：Sample Selection and Data Sources:
The catalyst used for growing SWCNTs is achieved by co-sputtering of Fe–Mo metals (
3：5 nm width) on a subsidiary cover of Al metal (10 nm width). List of Experimental Equipment and Materials:
The mass flow controller was used to control the supply of carrier gas Ar/H2 and the precursor gas C2H2 (acetylene) into the chamber. The PEI polymer layer was adsorbed on the surface of SWCNTs network by immersing in a PEI/methanol solution.
4：Experimental Procedures and Operational Workflow:
The sensors were dipped for 15 min, 1 and 2 h in a 20 wt% solution of PEI polymer. The sensors are taken out from the solution and the excess PEI is removed by rinsing the sample with the methanol.
5：Data Analysis Methods:
The change in the resistance of the SWCNTs sensor was recorded for various NO2 gas concentrations, such as 20 and 50 ppm.
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