以常壓熱化學氣相沉積法由乙炔成長奈米碳管之研究

Synthesis of Carbon Nanotubes over Sol-Gel Deposited Substrates from Acetylene by Thermal Chemical Vapor Deposition

韓世澤(Shih-Tse Hang) ； 葉競榮(Chin-Yung Yeh) ； 姚品全(Pin-Chuan Yao)

《科學與工程技術期刊》 3卷2期 (2007/06) Pp. 47-54

https://doi.org/10.7117/JSET.200706.0047

摘要

本研究以溶膠－凝膠法(sol-gel method)製備之鎳觸媒，旋轉塗佈於矽基板上，經線上還原後，以常壓熱化學氣相沉積法(atmospheric thermal CVD)由乙炔成長奈米碳管(carbon nanotubes, CNT)。研究結果發現：1.觸媒前處理時間、氣體流量、溫度、氣體種類、混合比等製程參數，可用以控制CNT之直徑。前處理溫度為800℃，添加氫氣最適作用時間約10~20分鐘；2.沉積反應條件之掌控對CNT產物的形態至為關鍵。成長溫度為800℃，此時成長速率最快，CNT在基板分佈密度最高；成長CNT時，添加氫氣有助於CNT管徑的控制，避免過多的竹節與彎曲形態產物發生；碳源與氫氣(C2H2/H2)最適比例約為0.1，如欲以thermal CVD系統達成奈米碳管的準直成長(aligned growth)，則必須更精確掌控金屬觸媒的分散狀態（顆粒大小、分佈均勻性等）及控制CNT的成長速度。所成長之奈米碳管，以拉曼光譜分析，顯示兩個峰值，分別是1305cm^(-1)與1560cm^(-1)，證明產物為多壁奈米碳管，含有多量的石墨態非晶形沉積物。

關鍵字

溶膠－凝膠法 ； 觸媒 ； 化學氣相沉積法 ； 奈米碳管

並列摘要

Nickel nanoparticles synthesized by a sol-gel process were spin-coated over silicon substrates as catalysts for the growth of a carbon nanotube (CNT) by atmospheric thermal chemical vapor deposition. The as-deposited Ni film exhibited relatively good activity for the growth of CNTs. On the basis of the results obtained, several characteristics of CNT growth were observed: Ⅰ. Pretreatment stage: Parameters including the reduction temperature, composition and flow rate of ambient gases had a prominent effect on the diameter and morphology of the as-grown carbon nanotube. A pretreatment temperature of 800℃ for 10~20 minutes seems adequate for CNT growth. Ⅱ. CNT growth stage: The temperature range for CNT growth extends from 700° to 900℃. For intensive growth and better quality control of the nanotube, it was beneficial to introduce a reduction ambient such as hydrogen flow. The optimal ratio of H2/C2H2 extends to within 0.1 under which CNT was grown at a considerable rate. Meanwhile, it took about 10~20 minutes for complete CNT growth under an ambient containing H2. For better control of the orientation of the as-grown CNTs (vertically aligned growth), information about the catalysts dispersion, growth rate control and how to prevent the deactivation of active sites during the growth stage would be necessary and vital. The Raman spectroscopy has strong bands at 1305 and 1560cm^(-1), respectively, thus providing definite evidence that the CNTs are multi-walled with a graphitic structure.

並列關鍵字

sol-gel method ； chemical vapor deposition ； carbon nanotubes