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In Situ TA-MS Study of the Six-Membered-Ring-Based Growth of Carbon Nanotubes with Benzene Precursor

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journal contribution
posted on 04.02.2004, 00:00 by Yajun Tian, Zheng Hu, Yong Yang, Xizhang Wang, Xin Chen, Hua Xu, Qiang Wu, Weijie Ji, Yi Chen
By using the in situ thermal analysis−mass spectroscopic technique, combined with transmission electron microscopic characterization of the carbon nanotube (CNT) product, we have studied the chemical vapor deposition (CVD) growth of CNTs with Fe−Co/γ-Al2O3 catalyst and benzene precursor in the range of room temperature to 700 °C. The growth process has been clearly illuminated, which starts from the reduction of catalyst around 645 °C followed by the dissociation of carbon−hydrogen bonds of benzene and the sequential growth of CNTs. A surprising fact is that no possible hydrocarbon species derived from benzene was detected, indicating that the carbon−carbon bond was not broken under our experimental conditions. All of the experimental results strongly reinforce the six-membered-ring-based growth model, and a schematic elucidation is presented accordingly. This in situ study not only reveals the unique and convincing information directly related to the growth mechanism from the involved chemistry, but also provides a powerful way to clarify the mechanism of CVD synthesis of CNTs with other precursors.