Yeoh, Wei-Ming and Lee, Kim-Yang and Chai, Siang-Piao and Lee, Keat-Teong and Mohamed, Abdul Rahman (2008) Synthesis of high purity multi-walled carbon nanotubes over Co-Mo/MgO catalyst by the catalytic chemical vapor deposition of methane. New Carbon Materials, 24 (2). 119 - 123.
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Official URL: http://www.sciencedirect.com/science/article/B8H10...
Thin-walled carbon nanotubes (CNTs) were prepared from methane decomposition using Ni/Mo/MgO as catalysts loaded with 1% mole fraction of Ni and smaller proportion of Mo. The relationship between CNT diameter and Ni/Mo ratio was studied by SEM, TEM, XRD and Raman spectroscopy. The particle size and the active phase of the catalyst could be modulated by the Ni/Mo ratio. With decreasing Ni/Mo ratio, a NiMo alloy was first formed, and then an isolated Mo phase was formed on the catalyst, as characterized by TEM and XRD. The NiMo alloy, with very small size, was responsible for the growth of thin-walled CNTs, whereas, the Mo phase was related to the formation of large-diameter thick-walled CNTs. The thin-walled CNTs with outer diameter of 3.0 nm and inner diameter of 1.3 nm could be obtained with high selectivity, a narrow diameter distribution, and high purity by controlling the Ni/Mo ratio at 6. Raman spectra confirmed the formation of thin-walled CNTs with few defects. The formation of thin-walled CNTs was mainly attributed to a rapid surface diffusion and precipitation of carbon on the small metal alloy crystallites.
|Uncontrolled Keywords:||Carbon Nanotubes; Chemical vapor deposition; Ni/Mo/MgO|
|Subjects:||Material Science > Nanofabrication processes and tools|
Material Science > Nanostructured materials
|Deposited On:||25 Mar 2010 22:05|
|Last Modified:||25 Mar 2010 22:05|
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