Electron microscope study of the formation of graphitic nanostructures in nickel-loaded wood char

Yumiko Kodama, Kazuhisa Sato, Kyoko Suzuki, Yukie Saito, Tsutomu Suzuki, Toyohiko J. Konno

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

We investigated the graphitization of carbonized larch wood chars impregnated with aqueous solution of nickel acetate, using scanning electron microscopy (SEM), both in secondary and transmission modes, and high-resolution transmission electron microscopy (HRTEM). Heat treatment of the chars at 500 °C brought about homogeneous distribution of metallic Ni particles about 5 nm in size in the amorphous carbon matrix. Graphitization sporadically started at this temperature, and some of the Ni particles are aggregated. SEM observations on chars heat-treated at 900 °C suggested that graphitic nanoshells about 50-200 nm in diameter, formed by catalytic effects of the Ni particles, grow in a "meandering" manner inside the amorphous carbon matrix. Some graphitic protrusions are found to grow outwards. Upon removal of the residual amorphous carbon matrix, long chains of the graphitic nanoshells exhibited a three-dimensionally intertwined structure, while transmission SEM showed that the interior of the shells is empty. HRTEM images exhibited not only stacked graphitic layers, but also cross-sectional contrasts expected from the hexagonal net of the graphite structure. These findings are discussed from the viewpoints of processing parameters, such as the use of aqueous solutions and atmosphere, specific to the catalytic graphitization of lignocellulosic materials.

Original languageEnglish
Pages (from-to)3486-3496
Number of pages11
JournalCarbon
Volume50
Issue number10
DOIs
Publication statusPublished - 2012 Aug 1

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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