Metal–semiconductor transition like behavior of naphthalene-doped single wall carbon nanotube bundles

Abstract

Naphthalene (N) or naphthalene-derivative (ND) adsorption-treatment varies evidently the electrical conductivity of single wall carbon nanotube (SWCNT) bundles over the wide temperature range due to charge transfer interaction. The adsorption treatment of SWCNT with dinitronaphthalene molecules enhances the electrical conductivity of the SWCNT bundles by 50 times. The temperature dependence of electrical conductivity of N-or ND-adsorbed SWCNT bundles having the superlattice structure suggests metal-semiconductor transition like behavior near 260 K. The ND-adsorbed SWCNT gives a maximum in the logarithm of electrical conductivity vs. T -1 plot, which may occur after the transition to a metallic state and be associated with a partial unraveling of the SWCNT bundle due to an evoked librational motion of the moieties of ND with elevation of the temperature.

Aqueous Nanosilica Dispersants for Carbon Nanotube

“…Here, S 11 and S 22 are the transition between the first and second van Hove singularities of the semiconductive SWCNTs, respectively, whereas M 11 is the transition between the first van Hove singularities of the metallic SWCNTs. 42,43 The observation of optical absorption spectra with distinct S 22 and M 11 peaks intrinsic to SWCNTs provides a strong evidence of a microscopically uniform dispersion of SWCNTs in the nanosilica solution. In addition, the intensity of the optical absorption spectrum increases with the silica concentration over the range of 0.001−0.01 wt %, giving a microscopic evidence that silica improves the dispersibility of SWCNTs in the aqueous phase.…”

“…Figure shows optical absorption spectra of SWCNT film with nanosilicas and that treated with 1 M HF. The spectrum of SWCNT treated with HF solution has clear three peaks at 0.71, 1.27, and 1.78 eV, which are assigned to S 11 , S 22 , and M 11 transitions, respectively. − …”

“…However, the peaks of SWCNT with nanosilicas are broad due to scattering by nanosilicas; the S 11 peak is quite weak and broad in particular. It is well-known that the charge transfer interaction of SWCNT with electron acceptors or donors does not reduce the S 22 and M 11 peaks, but the S 11 peak. − We can compare the peak intensity change of S 11 after normalization of the peak intensity of S 22 for SWCNT with nanosilica and SWCNT treated with HF solution, as shown in Figure S4. The presence of nanosilicas decreases significantly the intensity of the S 11 peak at 0.71 eV, which can be ascribed to the charge transfer interaction between SWCNT and nanosilica.…”

Ab initio study of hydrogen chemisorption in nitrogen-doped carbon nanotubes

“…In this sense, similar effects have been experimentally observed in bundles of SWCNTs with adsorbed naphthalene or naphthalene-derivatives. 33…”