奈米二氧化鈦基混成系統之二氧化氮氣體感測行為研究

Nitrogen Dioxide Gas Sensing Properties of Nanocrystalline TiO2-based Hybrid Systems

劉維人(Wei-Jen Liou)

指導教授 ： 林鴻明

大同大學/工程學院/材料工程學系所/博士(2007年)

摘要

本研究的主要動機在於開發有效率的氣體感測材料，用來監控有毒氣體，例如：一氧化碳、臭氣、氧化硫及氧化氮等，進而對環境的保護做出一些努力。
許多年來，部分半導體材料由於具有電阻變化的特性，成功地被用來偵測氣體。其中，金屬氧化物半導體(MOS)因為適合與電子裝置結合，因此吸引許多研究人員及使用者廣泛地將其應用在氣體感測器方面。
本研究藉由溶膠凝膠法製作出新型態的奈米混成材料：二氧化鈦/多壁奈米碳管以及二氧化鈦/碳黑。將前趨物鈦酸異丙酯(TIP)稀釋於異丙醇(IPA)中，再加入多壁奈米碳管或碳黑，經過攪拌及在氬氣氣氛下燒結後，形成二氧化鈦/多壁奈米碳管以及二氧化鈦/碳黑的奈米混成材料。
研究證明利用溶膠凝膠法可以在多壁奈米碳管以及碳黑的表面上披覆二氧化鈦層，且因為碳材料加入的混成作用，使得感測器具有較低的操作溫度，因此克服了純二氧化鈦無法在低溫下操作的缺點。本研究並依相同生成物之比例，以攪拌方式製成混合材料，與新型態二氧化鈦/碳黑進行比較。結果顯示不同製程會生成不同結構之奈米材料，進而展現出不同的感測特性。其中以二氧化鈦/碳黑(重量比4:1)之奈米混成材料在150℃感測時，對於二氧化氮具有較佳的穩定度及回復程度。這些結果說明此簡單又經濟的奈米材料製程將來應用在實際氣體感測器的可能性。

關鍵字

氣體感測器 ； 混成 ； 二氧化氮 ； 奈米碳管 ； 二氧化鈦 ； 碳黑

並列摘要

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.

並列關鍵字

gas sensor ； hybrid ； NO2 ； CNT ； TiO2 ； carbon black

參考文獻

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