奈米混成二氧化錫/奈米碳管氣體感測器之製備與特性研究

Fabrication and Properties of Nano Hybrid SnO2/CNTs Gas Sensor

陳彥菱(Yen-Ling Chen)

指導教授 ： 林鴻明

大同大學/工程學院/材料工程學系所/碩士(2006年)

摘要

近年來，隨著工業的進展及環保意識的重視，各種廢氣量日益增加，對於有毒氣體如CO, CO2, SO2, NO2等在環境的控制。它們對人體有害，此外對環境也造成傷害如酸雨主要酸的來源。藉由奈米材料製造技術，降低材料使用量和環境污染源。本研究是將奈米碳管在室溫下具有極佳的導電性和二氧化錫的對氣體反應靈敏特性做結合，使氣體感測器朝向應答速率快、元件製作容易及攜帶方便等優點。
奈米碳管為奈米結構具有非凡的電子和機械特性。奈米碳管的潛在應用包括微電子裝置、冷陰極平面顯示器(FPD)、儲氫、量子線、顯微鏡的掃瞄碳針和高能電化學電容器。由於奈米碳管具中空結構、奈米尺寸、大的表面積以及在室溫具有良好的導電性，因此成為吸收和偵測氣體理想的材料。此研究藉由奈米碳管複合半導體材料以改善氣體感測性質。應用溶膠凝膠法製造氧化錫，以二氯化錫為前驅物，覆蓋在酸處理後的多壁奈米碳管的表面上。在經過300℃或400℃熱處理後，可在奈米碳管表面上生成大小範圍為3到15 nm的氧化錫粒子。調整溶液中二氯化錫前驅物的濃度，可以控制不同厚度的二氧化錫薄膜披覆於奈米碳管表面。合成材料的特性經由X-ray, TEM, HRTEM, 及TGA-DTA進行分析。二氯化錫和混成二氯化錫/奈米碳管的材料，分別直接滴在金電極印刷的氧化鋁基板上，並在室溫下烘乾。奈米碳管的混成感測器加熱至400℃下持溫一天，使其材料結構穩定。之後探討合成材料在不同的NO2濃度10、30、50、100 ppm及不同的操作溫度50、100、150、200 ℃下材料的電特性。
實驗結果顯示氧化錫可藉由溶膠凝膠法成功包覆在奈米碳管的表面。且由混成二氧化錫/奈米碳管 (A4) 及 (B1) 的氣體感測結果顯示，隨著操作溫度的增加，靈敏度提高，而其最佳操作溫度在150 ℃。此混成奈米碳管材料不僅相對於傳統的純二氧化錫有更低的工作溫度，且在接近室溫時對於NO2具有感測特性。

關鍵字

二氧化錫 ； 奈米碳管 ； 氣體感測器

並列摘要

Recently, due to the industrial development and environmental protection pay much attention and various kinds of exhaust gas increase. The noxious gases such as CO, CO2, SO2 and NO2 control in the atmosphere. They are very toxic for human body and moreover with indirect harm to the environment such as main acidic species in acid rain. By producing the nanocrystalline materials decrease the material consumption and pollutant of environment. In this study, carbon nanotubes good conductivity at the room temperature combine with SnO2 high sensitive to gas and make gas sensor toward high response, easy manufacture and carry convenient.
Carbon nanotubes are nanostructures with remarkable electronic and mechanical properties. Potential applications of CNTs include microelectronic devices, cold cathode flat panel displays (FDP), hydrogen storage, quantum wires, tips for scanning probe microscopes and high power electrochemical capacitors. CNTs are ideal materials for adsorption and detection of gas due to their hollow center, nano-scale size, large specific surface area, and good conductivity at the room temperature. In this study, the hybrid CNTs with MOS material will be synthesized and examined its sensing properties. By sol-gel method using the precursor of Tin (Ⅱ) chloride, tin oxide is coated on acid-treated multi wall carbon nanotubes. After heat treatment at temperature 300℃ or 400℃, SnO2 particles form on the surface of carbon nanotubes with the sizes from about 3 to 15 nm. The contents of Tin (Ⅱ) chloride in solution are used to adjust the thickness of SnO2 films on carbon nanotubes. The characteristic of this hybrid materials are analysis by X-ray diffraction, SEM, HRTEM, and TGA-DTA. The pure SnO2 and SnO2/MWCNTs are separated coated on the Au electrodes printed alumina substrates in dry atmosphere at room temperature. Hybrid SnO2/MWCNTs sensor heated at 400℃ for one day to stabilize the structure of sensor. Nano hybrid SnO2/MWCNTs and SnO2 sensors detect various concentrations of NO2 from 10 to 100 ppm at different working temperatures of 50℃, 100℃, 150℃and 200℃.
Experimental results indicate it is possible to coating the nano SnO2 on the surface of carbon nanotubes by the sol-gel method. Sensitivities of SnO2/MWCNTs (A4) and (B1) are enhanced and the optimum working temperature is about 150 ℃. It shows the hybrid SnO2/MWCNTs decrease the sensing operation temperature and enhance the gas sensitivity for NO2 gas at room temperature.

並列關鍵字

SnO2 ； CNTs ； Gas Sensor

參考文獻

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