Synthesis of carbon nanotubes on Ni/carbon-fiber catalysts under mild conditions

Kiyoshi Otsuka, Yoshimune Abe, Nobuhiro Kanai, Yoji Kobayashi, Sakae Takenaka, Eishi Tanabe

Research output: Contribution to journalArticlepeer-review

80 Scopus citations

Abstract

Methane, n-hexane, benzene, and cyclopentadiene were decomposed at a relatively mild temperature (773 K) over a Ni catalyst supported on either vapor grown carbon fibers (VGCF) or graphitized carbon fibers (GCF). Transmission electron microscopy showed that the morphology of the fibers changed according to hydrocarbon and particle size. Decomposition of methane and n-hexane produced fishbone-type fibers. The fibers from n-hexane sometimes showed intermittent hollow structures but the diameters of the fibers were widely distributed. Decomposition of benzene and cyclopentadiene mainly produced winding type carbon nanotubes of relatively uniform diameters (10-20 nm). Bidirectional fishbone-type fibers (fibers growing outward from a central catalyst particle) were also observed as a by-product. Small Ni particles (10-20 nm) with stretched tails were present on the tips of tubular fibers, some of which frequently changed growth direction. The varying tubular morphologies can be ascribed to liquid-like Ni particles resulting from the freezing point depression due to a fast dissolution of carbons during decomposition of benzene or cyclopentadiene. The formation of bidirectional fibers was also observed in the decomposition of n-hexane. Relatively large well-faceted Ni particles (diameter 50-110 nm) grew bidirectional fibers. © 2004 Elsevier Ltd. All rights reserved.
Original languageEnglish (US)
Pages (from-to)727-736
Number of pages10
JournalCarbon
Volume42
Issue number4
DOIs
StatePublished - Apr 2 2004
Externally publishedYes

Bibliographical note

Generated from Scopus record by KAUST IRTS on 2022-09-13

ASJC Scopus subject areas

  • Chemistry(all)

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