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Development of Multi-Walled Carbon Nanotubes Film for Ionization based Gas Sensing Application

Thaha, Hendrayana (2008) Development of Multi-Walled Carbon Nanotubes Film for Ionization based Gas Sensing Application. Masters thesis, Universiti Teknologi Petronas.

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Nowadays many types of gas sensors have been used to identify and detect the presence of various gases in industrial plants. However, these gas sensors are still facing the problem of lack selectivity and sensitivity for gas detection in ambient temperature and also slow in response time. The objective of this research is to develop multi-walled carbon nanotubes (MWCNTs) film for ionization based gas sensing application. In this study, MWCNTs film is proposed to be used as the active component due to its remarkable electronic and field emission properties for generating ionization mechanism on the gas. MWCNTs were synthesized by the decomposition of ethylene over metal coated, oxidized silicon substrate in thermal chemical vapor deposition CVD system. Structure and morphology of grown MWCNTs were examined using Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) whilst the electrical properties of nanotubes film were characterized by Van der Pauw and Hall Eff()ct technique. Gas sensing properties testing ofMWCNTs film are carried out by identifying gas breakdown voltage between nanotubes film cathode and aluminum film anode. Gasses that have been tested are helium, argon, air, hydrogen 2% in air mixture, and ammonia. MWCNTs grown using this CVD technique are found to have high crystallinity with typical diameter of 18 nm and length of 1.5 Jlm. Testing the sensing properties at room temperature reveals that the utilization of MWCNTs film as cathode was able to scale down the air breakdown voltage by a factor of about 58 % as compared to aluminum cathode. On the I 0 mL gas volume, helium gas gives the lowest breakdown voltage of about 134 V, whilst air gives the highest value of about 320 V. Further experiment shows that the breakdown volt,.ge is not significantly affected by the gas volume content in testing chamber. Reducing 'he interelectrode separation by 60 Jlm results the lowering of the breakdown voltage of helium gas by 122 V. It is concluded that utilization of MWCNTs film as cathode in the ionization based gas sensing configuration is capable to detect helium, argon, air, 2% hydrogen in air mixture, and ammonia at room temperature.

Item Type: Thesis (Masters)
Academic Subject : Academic Department - Electrical And Electronics - Pervasisve Systems - Digital Electronics - Test and Reliablity
Subject: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: Engineering > Electrical and Electronic
Depositing User: Users 2053 not found.
Date Deposited: 09 Oct 2013 11:07
Last Modified: 25 Jan 2017 09:45
URI: http://utpedia.utp.edu.my/id/eprint/8284

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