Electrochemical tuning of electronic structure of carbon nanotubes and fullerene peapods

• Published in: Carbon (New York) 2004, Vol.42 (5), p.1011-1019
• Main Authors: Kavan, L, Dunsch, L, Kataura, H
• Format: Article
• Language: English
• Subjects: A. Fullerene, Carbon nanotubes; B. Electrochemical analysis, Raman spectroscopy; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Physics; Specific materials
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2003.12.024

Single-wall carbon nanotubes, fullerene peapods (C 60@SWCNT, C 70@SWCNT) and double-wall carbon nanotubes can be charged electrochemically in various media, such as acetonitrile electrolyte solutions or 1-butyl-3-methylimidazolium tetrafluoroborate/hexafluorophosphate melts (ionic liquid). Electrochemistry of nanotubes and peapods is dominated by their capacitive double-layer charging. In-situ Vis-NIR spectra of nanotubes and peapods demonstrate reversible bleaching of the allowed optical transitions between van Hove singularities. The bleaching of optical transitions, induced by charge-transfer, is mirrored by quenching of resonance Raman spectra in the region of tube-related modes. The Raman modes of intratubular C 60 in peapods exhibit considerable intensity increase upon anodic doping, but these modes are not enhanced at cathodic charging. The “anodic Raman enhancement” is specific for C 60@SWCNT only. In the case of C 70@SWCNT, symmetric quenching of the C 70 Raman modes is detected at both cathodic and anodic potentials. Electrochemical charging in DWCNT points at specific response of the inner and outer tubes, the latter being more sensitive to doping.