Characterization of single wall carbon nanotubes by means of rare gas adsorption

Abstract

Based on the formalisms of Langmuir and Fowler, theoretical adsorption isotherms are calculated for different bundle geometries of single wall carbon nanotubes in a triangular lattice. The authors show the dependence of the adsorption properties on the nanotube diameter and on the specific morphology of the bundles they constitute. The authors demonstrate how isotherm curve analysis can help to experimentally determine what kinds of tubes form a given bundle and the ratio of open to closed tubes in a sample having undergone a complete or incomplete opening protocol. In spite of the model's simplicity, quite satisfactory agreement is observed between experiments and the authors' calculations.

Electrical properties and reactivity under air–CO flows of composite systems based on ceria coated carbon nanotubes

“…2 represents the typical X-ray diffraction patterns obtained from the pure nanocrystalline ceria sample, and for the x = 15 wt.% composite sample. In full agreement with literature results [17][18][19]32], the two characteristic Bragg peaks of CNTs corresponding to the (0 0 2) and the (1 0 1) in the XRD pattern, are observed in this last sample close to the angle of 2 = 26.5 • . The ceria polycrystalline phase is clearly evidenced through the Bragg peaks of fluorite structure (JCPDS 89-8436): these diffraction peaks are systematically broadened, which confirms the nanostructuration of ceria phase.…”

“…This approach based on precipitation way is reported in previous works by several authors using carbon nanotubes (multi wall) [17][18][19][20] and anodic alumina membrane (AAM) [27] as template method. In our work, DWNTs are used as support for ceria nanoparticles.…”

“…CNTs based materials have attracted many technological and scientific interests: due to their remarkable properties linked to their tubular form and their nanoscale [11,12], they could offer exciting possibilities for a lot of applications including miniaturized and faster electronic devices. Carbon nanotubes seem also to be ideal for adsorption [13][14][15][16], sieving [17] and gas detection [18][19][20][21], due to their high specific surface and porosity. Chemical functionalization of carbon nanotubes would allow enhancing their electrical conductivity and generating new properties.…”

Accessibility of Nanotube Inner Channels Investigated by Krypton Adsorption

“…Each adsorption isotherm exhibits two inclined steps, which is consistent with previous findings on gas adsorption on SWCNTs. 6,7,[13][14][15][16] In the case of formation of successive condensed monolayer on the same adsorption sites (Kr adsorption on exfoliated graphite for example [17][18][19] ) the step heights are identical because each adsorbed layer corresponds to condensation of the same adsorbate amount. On the other hand, in our case, we clearly observe that the heights of the first and second steps are not equal.…”

“…Concerning the interstitial channels, even if Kr atoms are small enough to enter, the associated adsorption energy is so low, that their adsorption can be neglected. 16 The BET method gives a specific surface area (SSA) of (420 ± 20) m 2 /g for the raw sample. This is in good agreement with the work of Krungleviciute et al, 20 in which surface area measurements were determined via four different adsorbates: neon, argon, xenon, and methane.…”