現今的環境工程領域中，奈米碳管或奈米碳材料廣泛被研究及應用於去除水中污染物，然而在奈米碳管中於氣態污染物的應用研究相對較少。一般以氣相層析儀或高效能液相層析儀作酚氣體檢測分析，雖具有高靈敏度、高準確性，這些分析方法尚有一些缺點，如體積龐大、儀器成本高、檢測速度慢。然而，以奈米碳管或奈米碳材製成氣體感測器優點，如體積小及檢測快速。因此，應用奈米碳管為酚類氣體感測器可改善及發展成具有重要意義。本研究目的在於建立一套最佳的方法來生成奈米碳管，將此製作一可應用為氣體感測元件，將此元件作氣體感測之初步測試。本研究分為三個階段實驗，第一階段分別以三種不同披覆催化劑之方法來披覆催化於載體表面（溶膠凝膠法、蒸鍍法、有機金屬裂解法）。第二階段於常壓狀態下，以熱化學氣相沉積法作生成奈米碳管之研究。第三階段，氣體感測器之感測研究，以酚氣體作靈敏度感測測試。這三個主要的研究結果顯示，第一階段，以蒸鍍法披覆比溶膠凝膠法及有機金屬裂解法均勻；另外以有機金屬裂解法產生金屬結晶顆粒效果最佳。第二階段，以有機金屬裂解法在熱化學氣相沉積法中為生成奈米碳管方法中生成密度及產率為最佳。利用掃描式電子顯微鏡及穿透式電子顯微鏡，觀察其奈米碳管結構圖，在奈米碳管的層與層之間距為0.34 nm，直徑為42.8 nm，中空結構為10.5 nm，而其長度為nm到μm之間。最後階段研究結果發現，以奈米碳管作氣體感測器，於高濃度(1000 ppmv)狀態下酚氣體，對其靈敏度可達到13%。本研究結論，於常壓狀態下利用熱化學氣相沉積法，以有機金屬裂解法生成奈米碳管於載體上，為最佳生成方法。另外，奈米碳管對於高濃度酚氣體之氣體感測器中，具有高靈敏度。這將有助於改善氣體感測器在未來應用上的研究。 In the current environmental engineering field, carbon nanotubes (CNT) or carbon nano-materials are widely studied and applied to treat water pollutants. There are relatively few researches in the application of carbon nanotubes in gaseous pollutants, particularly as a sensor device for organic vapors. Although gas chromatography or high-performance liquid chromatography is commonly used to test and analyze gas-phase phenol because of its high levels of sensitivity, these analytic methods are expensive and time-consuming. Gas sensors made of CNTs or carbon nano-materials can provide relatively inexpensive and rapid testing time. Therefore, the overall objective of this research is to develop an optimal method to grow CNTs that can enhance the sensitivity of gas sensors. Three studies were carried out for three research goals: 1) “Substrate Preparation Study” was to develop the best coating method to prepare substrate with three coating catalyst methods (i.e., sol-gel method, vapor deposition method, and metal organic decomposition method); 2) “CNT Growth Study” was to develop the optimal CNT growth conditions using thermal chemical vapor deposition (TCVD) process under atmospheric pressure; 3) “Gas Sensor Sensitivity Study” was to perform preliminary sensitivity test of gas sensors for phenol gas.The results of these studies show three primary findings. First, while vapor deposition method was a better method than MOD and the sol-gel method in terms of surface uniformity, MOD was a better method in terms of metal particle distribution over the substrate surface. Second, MOD combined with TCVD was a better method in terms of productivity and density of CNT. Observing the image of MWCNT structure using electron microscopes, the MWCNT layer and the layer spacing was 0.34 nm, the average outer and inner diameters were 42.8 nm and 10.5 nm, and the scale of the length ranged from hundreds of nanometer to several micrometers. The result of the last part of the study showed that the gas sensor sensitivity can achieve up to 13% in the high concentration of phenol gas (1000 ppmv).This research concludes that the optimal method to grow CNT was to use MOD to prepare substrate and to use TCVD-atmospheric pressure. In addition, the synthesized CNTs can provide the high sensitivity of gas sensor for high concentration of phenol gas, which can contribute to the improvement of the quality of gas sensor in the future.
