Chemically Doped Double-Walled Carbon Nanotubes: Cylindrical Molecular Capacitors

Abstract

A double-walled carbon nanotube is used to study the radial charge distribution on the positive inner electrode of a cylindrical molecular capacitor. The outer electrode is a shell of bromine anions. Resonant Raman scattering from phonons on each carbon shell reveals the radial charge distribution. A self-consistent tight-binding model confirms the observed molecular Faraday cage effect, i.e., most of the charge resides on the outer wall, even when this wall was originally semiconducting and the inner wall was metallic.

Raman bands of double‐wall carbon nanotubes: comparison with single‐ and triple‐wall carbon nanotubes, and influence of annealing and electron irradiation

“…The disappearance of the D band after annealing proves that defective regions are oxidized by annealing. 17 The observation of RBMs with similar intensities shows that the diameter distribution probed at 647 nm has not changed.…”

“…18 Doping influences the population of the electronic states and leads to charge transfer. 17,20 and intensity transfer from the G band, associated with the outer tube, to other spectral bands have been suggested. 15,21 The D band contains several spectral components related to the double resonant process and the presence of Van Hove singularities in CNTs.…”

“…The wavenumbers of both the inner and outer tubes have been estimated earlier using doped DWCNTs. 17 While the G-band shape from DWCNTs obtained with peapods changes with the excitation energy, DWCNTs grown by the CCVD method are less sensitive to the excitation energy. 18 Doping influences the population of the electronic states and leads to charge transfer.…”

X-ray diffraction as a tool for the determination of the structure of double-walled carbon nanotube batches

“…3 Pairs of tubes in DWCNTs can also be evidenced through Raman radial breathing mode ͑RBM͒ frequencies. 1,2,8,14 However, this technique is not straightforward for giving a quantitative characterization of a sample due to resonance effects, which make a large number of nanotubes invisible in the Raman response of a sample. Moreover, the penetration depth of visible lasers into nanotubes is too low to allow a global characterization of a macroscopic sample.…”

Funcionalização de nanotubos de Carbono

“…Semelhante à química de intercalação do grafite, os nanotubos de carbono também têm sido intercalados com espécies receptoras, tais como os elementos halogênios 49,53,54 . Estudos de espectroscopia Raman ressonante mostram que nanotubos interagindo com I 2 e Br 2 atuam como doadores de carga para essas moléculas 49 .…”