High growth of SWNTs and MWNTs from C₂H₂ decomposition over Co–Mo/MgO catalysts

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• 作者：Shajahan ; Md. ; Mo ; Y.H. ; Fazle Kibria ; A.K.M. ; Kim ; M.J. ; Nahm ; K.S.
• 关键词：A. Carbon nanotubes ; B. Chemical vapor deposition ; C. X-ray diffraction ; Raman spectroscopy ; D. Carbon yield
• 刊名：Carbon
• 出版年：2004
• 期刊代码：10_00086223
• 类别：ms
• 出版时间：2004
• 卷：42
• 期：11
• 页码：2245-2253
• 文件大小：663 K

摘要

A series of MgO supported catalysts having Co and Mo metals 5–40 wt.%in a ratio of 1:1 was prepared by impregnation method. Carbon nanotubes (CNTs) were grown over the catalysts by decomposition of C₂H₂ at 800 °C for 30 min. It was found that 5 and 10 wt.%Co–Mo/MgO catalysts produced single-wall nanotubes (SWNTs), whereas 20, 30 and 40 wt.%Co–Mo/MgO catalysts produced multi-wall nanotubes (MWNTs). The catalyst Mo/MgO was inactive in growing CNTs. In Co–Mo/MgO catalysts, however Mo generated a favorable environment to grow SWNTs. The growth of SWNTs was strongly dependent on the formation of small clusters of cobalt, which may generate from the decomposition of CoMoO₄ species during the nanotube growth. MWNTs were produced over comparatively larger cobalt clusters generated from Co₃O₄ phase during the nanotube growth stage. The yields of SWNTs were about 6%and 27%over 5 and 10 wt.%Co–Mo/MgO catalysts, respectively. MWNTs yield (576%) was observed over 40 wt.%Co–Mo/MgO catalyst. Carbon yield (%) highly varied with acetylene concentration.