Observation of micropores in hard-carbon using 129Xe NMR porosimetry

Kazuma Gotoh, Takahiro Ueda, Hironori Omi, Taro Eguchi, Mariko Maeda, Michihisa Miyahara, Aisaku Nagai, Hiroyuki Ishida

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The existence of micropores and the change of surface structure in pitch-based hard-carbon in xenon atmosphere were demonstrated using 129Xe NMR. For high-pressure (4.0 MPa) 129Xe NMR measurements, the hard-carbon samples in Xe gas showed three peaks at 27, 34 and 210 ppm. The last was attributed to the xenon in micropores (<1 nm) in hard-carbon particles. The NMR spectrum of a sample evacuated at 773 K and exposed to 0.1 MPa Xe gas at 773 K for 24 h showed two peaks at 29 and 128 ppm, which were attributed, respectively, to the xenon atoms adsorbed in the large pores (probably mesopores) and micropores of hard-carbon. With increasing annealing time in Xe gas at 773 K, both peaks shifted and merged into one peak at 50 ppm. The diffusion of adsorbed xenon atoms is very slow, probably because the transfer of molecules or atoms among micropores in hard-carbon does not occur readily. Many micropores are isolated from the outer surface. For that reason, xenon atoms are thought to be adsorbed only by micropores near the surface, which are easily accessible from the surrounding space.

Original languageEnglish
Pages (from-to)147-152
Number of pages6
JournalJournal of Physics and Chemistry of Solids
Volume69
Issue number1
DOIs
Publication statusPublished - Jan 2008

Keywords

  • A. Amorphous materials
  • A. Microporous materials
  • D. Nuclear magnetic resonance (NMR)

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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