| Abstract
| - We studied the influence of ethylene and hydrogen flow rates on the properties of carbon nanotubes (CNTs) and synthesized millimeter-long carbon nanotube arrays (CNTAs) by optimizing the ethylene and hydrogen flow rates. Our results show that the wall number, crystallinity of the graphene sheets, and length of CNTs are greatly influenced by ethylene and hydrogen flow rates. Small ethylene flow or large hydrogen flow tends to synthesize CNTs with small diameters and few walls, and even single- and double-walled CNTs can be prepared by tuning the flow rates. These results indicate that that accurate regulation of carbon source and hydrogen flow rate, which is a simple and versatile method, enables selective synthesis of various types of CNTAs. The possible mechanism of the influence of ethylene and hydrogen flow rates on CNT growth is proposed and discussed for a better understanding of these phenomena.
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