以化學氣相沉積法在氧化鎂觸媒載體上成長單層奈米碳管

Synthesis of Single Walled Carbon Nanotubes upon Magnesium Oxide by Catalytic Chemical Vapor Deposition

簡滙宏(Hui-Hung Chien)

指導教授 ： 曾信雄

大同大學/工程學院/材料工程學系所/碩士(2004年)

摘要

奈米碳管（Carbon nanotube, CNT）乃是在1991年由Iijima所發現的。因為其特殊的結構造成許多不同優越的性質，因此可應用在許多的領域上面。影響奈米碳管成長的製程參數，包括沉積溫度、壓力、碳源種類、流量變化與沉積時間等因素，在本實驗中，吾人使用氧化鎂粉末當作鈷催化劑載體，並對於催化劑濃度、沉積時間、甲烷流量、成長溫度、氫氣影響與催化劑比表面積影響等六種參數來加以討論並藉此找到最佳的參數。結果發現以化學氣相沈積方式在氧化鎂之載體上能相當成功地成長出奈米碳管，而這些奈米碳管絕大部分為單層碳管，並因為凡德瓦爾力的關係，傾向於變成集束狀的型態，根據Raman光譜與TEM的結果得到其單根單層碳管的直徑約為0.86-1.23nm。在催化劑濃度為1.5、2.5及5wt%所得到的碳管產量較高；當成長時間過久時碳原子會向兩碳管束的交接處或是在靠近氧化鎂上所成長的碳管上進行增厚。另外在900℃所成長的結果因為比較沒有碳沈積在氧化鎂的表面上，所以經由鹽酸酸洗後發現在不破壞碳管結構的情形下，即能輕易地將氧化鎂粉末移除掉。

關鍵字

氧化鎂 ； Raman 光譜 ； 單層奈米碳管

並列摘要

Carbon nanotubes（CNTs）were discovered by Iilima in 1991, they have attracted worldwide attentions due to their excellent properties by their special structures. The processing parameters of growing carbon nanotubes include the deposition temperature, deposition pressure, types of the carbon sources, flow rate and deposition time etc. In this study, we used the magnesium oxide as the substrate of the cobalt catalysts and we investigated the effects of the following parameters, including the catalyst concentration, deposition time, the methane flow, deposition temperature, the hydrogen flow and the specific surface area. Experimental results indicated that carbon nanotubes can be synthesized successfully upon the magnesium oxide by catalytic chemical vapor deposition. These carbon nanotubes were almost the single walled carbon nanotubes（SWNTs）and tend to align together to form a bundle morphology. From the Raman spectra and TEM, the diameter of the SWNTs was about 0.86-1.23nm. The yield of CNTs was better as the catalyst with concentrations of Co/MgO=1.5, 2.5 and 5wt%. Besides, the CNTs were thickened for a long deposition time. And the acid treatment of the as-grown samples in 900℃ was efficient for removing the magnesium oxide without damaging the CNTs structures because that there was no deposition of amorphous carbon on the magnesium oxide.

並列關鍵字

Magnesium Oxide ； Raman spectra ； Single-walled carbon nanoubes

參考文獻

[3] M.S.Dresselhaus, G.Dresselhaus, and R.Saito, in Carbon Nanotubes, edited by

[4] Dai Hongjie,“ Nanotube Growth and Characterization”in Carbon Nanotubes

synthesis structure properties and applications, edited by M.S.Dresselhaus,

R.Beyers, Nature 363（1993）605.

J. Phys. Chem. B 105（2001）9699.