Chemistry of water-assisted carbon nanotube growth over Fe-Mo/MgO catalyst

Naoki Yoshihara, Hiroki Ago, Masaharu Tsuji

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    49 Citations (Scopus)

    Abstract

    Introducing a small amount of water vapor in the catalytic chemical vapor deposition (CVD) growth of singleand double-walled carbon nanotubes (SWNTs and DWNTs) extends the catalyst lifetime and increases the nanotube yield. We study the mechanism of this water-assisted nanotube growth over a Fe-Mo/MgO catalyst, based on analysis of the effluent gas, in terms of chemistry of the water-induced oxidation and its effects on catalytic activity. Water vapor was found to etch away carbon precipitate covering the metal catalyst, based primarily on the chemical reaction C + H2O → CO + H2, thus maintaining the catalytic activity. This oxidative etching was strongly dependent on the CVD temperature, and the balance between the etching and carbon precipitation was important for effective nanotube growth. With an optimized water concentration, the etching rate of the carbon precipitate was estimated to be ca. 1/1000 of the formation rate of carbon precipitate consisting mainly of SWNTs and DWNTs.

    Original languageEnglish
    Pages (from-to)11577-11582
    Number of pages6
    JournalJournal of Physical Chemistry C
    Volume111
    Issue number31
    DOIs
    Publication statusPublished - Aug 9 2007

    All Science Journal Classification (ASJC) codes

    • Electronic, Optical and Magnetic Materials
    • Energy(all)
    • Physical and Theoretical Chemistry
    • Surfaces, Coatings and Films

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