Probing charge transfer between shells of double-walled carbon nanotubes sorted by outer-wall electronic type

Martin Kalbac, Alexander A. Green, Mark C. Hersam, Ladislav Kavan

Research output: Contribution to journalArticle

21 Scopus citations


Double-walled carbon nanotubes (DWCNTs) with outer metallic (M) or semiconducting (S) shells were sorted by density-gradient ultracentrifugation and examined by Raman spectroscopy and in situ Raman spectroelectrochemistry. The combination of sorting and the selection of appropriate laser excitation energies allowed the disentanglement of the effects of different variations of the electronic type (M or S) of the inner and outer tubes in DWCNTs on the doping behavior and charge transfer between the inner and outer walls. Charge transfer from the outer tube to the inner tube occurs only if the electronic states of the outer tube are filled with electrons or holes, and if these filled states are higher in energy than those of the inner tube. Therefore, each combination of inner and outer tube (i.e., inner@outer: M@M, M@S, S@M, and S@S) exhibits a distinct behavior. The potential needed to observe the effects of charge transfer between the inner and outer tubes is found to increase in the following order: M@M < S@M < M@S < S@S.

Original languageEnglish (US)
Pages (from-to)9806-9815
Number of pages10
JournalChemistry - A European Journal
Issue number35
StatePublished - Aug 22 2011
Externally publishedYes



  • Raman spectroscopy
  • density-gradient ultracentrifugation
  • double-walled carbon nanotubes
  • electrochemistry
  • nanotubes

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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