| Summary: | 博士 === 大同大學 === 材料工程學系(所) === 95 === The main motivation of this study is developing effective gas sensors to monitor harmful gases, such as carbon monoxide (CO), ozone (O3), sulfur oxides (SOx) and nitrogen oxides (NOx), so that to make some contribution in protecting the environment.
Gas sensors based on resistance changes of selected semiconductor materials have been successfully used for many years. Metal oxide semiconductor (MOS) attracts considerable interests to both researchers and users due to their suitabilities for using in electronic devices in a number of applications including gas sensors.
This study presents new nano hybrids of TiO2/multi-walled carbon nanotubes (MWCNTs) and TiO2/carbon black synthesized via a sol-gel process. Titanium tetra-isopropoxide solution is used as the precursor for sol-gel synthesis, and diluted with isopropyl alcohol (IPA). A preliminary solution of MWCNTs or carbon black diluted in IPA is added during sol-gel preparation. After stirring and calcining under argon atmosphere, nano hybrids of TiO2/MWCNTs or TiO2/carbon black are formed.
The results show successful coating of TiO2 on MWCNTs or carbon black with sol-gel technology. With the process of carbon-hybridization, the operative temperatures of sensors can be decreased, which overcome the disadvantage of pure TiO2 gas sensor that can not work at low temperatures. In this study, a mixture fabricated by stirring is used to compare with hybrid TiO2/carbon black with the same kinds and amounts of components. The results show that different structures made by dissimilar fabrications have diverse properties. The new hybrid with 80 % TiO2 and 20% carbon black has better sensing properties including stabilities and recovery degrees than others. This study shows the possibilities of practical applications of nano TiO2/carbon black sensors fabricated by the easy and cheap method.
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