Carbon Atoms in Ethanol Do Not Contribute Equally to Formation of Single-Walled Carbon Nanotubes

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• 作者：Rong Xiang ; Bo Hou ; Erik Einarsson ; Pei Zhao ; Sivasankaran Harish ; Kenichi Morimoto ; Yuhei Miyauchi ; Shohei Chiashi ; Zikang Tang ; Shigeo Maruyama
• 刊名：ACS Nano
• 出版年：2013
• 出版时间：April 23, 2013
• 年：2013
• 卷：7
• 期：4
• 页码：3095-3103
• 全文大小：506K
• 年卷期：v.7,no.4(April 23, 2013)
• ISSN：1936-086X

文摘

We propose a unique experimental technique in which isotopically labeled ethanol, e.g., ¹²CH₃鈥?sup>13CH₂鈥揙H, is used to trace the carbon atoms during the formation of single-walled carbon nanotubes (SWNTs) by chemical vapor deposition (CVD). The proportion of ¹³C is determined from Raman spectra of the obtained SWNTs, yielding the respective contribution of ethanol鈥檚 two different carbon atoms to SWNT formation. Surprisingly, the carbon away from the hydroxyl group is preferably incorporated into the SWNT structure, and this preference is significantly affected by growth temperature, presence of secondary catalyst metal species such as Mo, and even by the substrate material. These experiments provide solid evidence confirming that the active carbon source is not limited to products of gas-phase decomposition such as ethylene and acetylene, but ethanol itself is arriving at and reacting with the metal catalyst particles. Furthermore, even the substrate or other catalytically inactive species directly influences the formation of SWNTs, possibly by changing the local environment around the catalyst or even the reaction pathway of SWNT formation. These unexpected effects, which are inaccessible by conventional techniques, paint a clearer picture regarding the decomposition and bond breaking process of the ethanol precursor during the entire CVD process and how this might influence the quality of the obtained SWNTs.

Keywords:

single-walled carbon nanotube; growth mechanism; isotope labeling; precursor decomposition