摻雜金銀之二氧化錫薄膜對一氧化碳偵測性質之研究

Study on the Gold, Silver Doped Tin Oxide Films and Its Sensing Performance of Carbon Monoxide

李孟軒(Meng-Syuan Li)

指導教授 ： 周更生

國立清華大學/工學院/化學工程學系/碩士(2007年)

摘要

摘要

在這篇論文中主要研究目標為將催化一氧化碳之觸媒應用在氣體感測器機制中，藉由提升感測樣品表面孔隙度以及增加與一氧化碳反應的能力，提高感測器的靈敏度，其中靈敏度和表面薄膜厚度、比表面積、孔隙度、感測器操作溫度、摻雜金屬種類皆有關係；因此吾人希望利用上述種種性質發展出優質的一氧化碳感測器。
實驗進行步驟首先藉由溶膠凝膠法合成二氧化錫粉末，此粉末藉由BET篩選出高比表面積、與具備較高孔隙的粉末，將此粉末加入PVB與部分溶劑作為成膜漿料，成膜後高溫移除此溶劑及高分子，在SEM下觀察發現擁有良好孔隙的結構，之後藉由含浸法(Dip-coating)將此膜含浸於銀奈米粒子溶液中以摻雜銀；濺鍍法(Sputtering)鍍上少許金奈米粒子；最後將含金銀奈米粒子的二氧化錫薄膜置入反應器中，通入不同濃度一氧化碳與不同的感測溫度環境下，量測靈敏度與反應時間等性質的變化情形，實驗結果發現電阻變化量受通入一氧化碳濃度與摻雜金銀奈米粒子所影響，而反應時間則受操作溫度與摻雜金屬所影響；未摻雜的二氧化錫薄膜在低溫的靈敏度與反應時間皆不理想，加入金奈米粒子改善後提升了靈敏度，但卻因為金本身幫助一氧化碳吸附的能力，造成恢復時間增加，此缺點經過掺入能幫助吸附氧氣離子的奈米銀粒子後可獲得改善，而在低溫下與較低濃度一氧化碳環境中，加入金銀的二氧化錫薄膜仍可擁有良好靈敏度與較短反應時間與恢復時間。

關鍵字

二氧化錫 ； 一氧化碳 ； 金銀

並列摘要

Abstract
The SnO2 powders were synthesized by sol-gel method in this work. By BET analysis, we chose the proper powders with high specific surface area and porosity for the following application. Next, the selected powders were mixed with PVB and solvent to make a paste. The paste was coated onto the Al2O3 substrate by spin coating to make a thin film, and subsequently treated with calcination at high temperature to remove the solvent and polymer. It was confirmed by SEM that the calcined SnO2 thin film was a well porous structure. In addition, we doped the thin film with Au by sputtering and with Ag by dip-coating, in which the thin film was dipped in the Ag colloidal suspension. Then, the Au/Ag-doped SnO2 thin film was fixed in the bottom of the reactor, inputted with CO gas and meanwhile recorded the corresponding change of sensitivity and reaction time at various concentrations. We found that sensitivity was affected by CO concentration, while reaction time was affected by operating temperature, and both of them were affected by Au and Ag. In our experiment, the SnO2 thin film doped without any dopants of Au and Ag showed unacceptable result of sensitivity as well as reaction time at low temperature. Although its sensitivity could be raised by doping with Au, however, that increased the recovery time due to the well adsorbing ability of CO for Au, could be improved by doping additional Ag which is helpful to adsorb O2-. Therefore, SnO2 thin film doped with both Au and Ag could show excellent sensitivity, short reaction and recovery time at low temperature and CO concentration.

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工業安全衛生技術發展中心

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