Single-walled carbon nanotubes in superacid: X-ray and calorimetric evidence for partly orderedH2SO4

Abstract

(2005). Single-walled carbon nanotubes in superacid: X-ray and calorimetric evidence for partly ordered H 2 SO 4 . Retrieved from

Single-Walled Carbon Nanotube-Templated Crystallization of H2SO4: Direct Evidence for Protonation

“…The anisotropic scattering is solely from the structured acid associated with wellaligned nanotubes. 2 Upon cooling to 100 K or heating to 500 K (experimental limits), no change of the scattering pattern was observed, strongly suggesting that the acid associated with nanotubes remains partly ordered. This is consistent with our previous DSC results which show no signature of a phase transition between 170 and 300 K. 2 The high stability of the partly ordered acid phase implies that the association between nanotubes and the structured sulfuric acid is relatively strong.…”

“…1,2 Calorimetric and X-ray diffraction data indicate a new phase of H 2 SO 4 molecules surrounding the tubes as cylindrical shells. 2 We show here that the SWNT/H 2 SO 4 interaction also induces short-range orientational order 3 which templates the crystallization of free acid with specific orientations.It was proposed that direct protonation of SWNTs is responsible for the formation of acid layers and consequently the dissolution of nanotubes, 4 but there is little direct evidence for this model. It is difficult to distinguish protonation from redox doping as in acidtreated SWNTs.…”

“…Dissolved in anhydrous sulfuric acid, they induce a partial positional order in the surrounding solvent molecules. 1,2 Calorimetric and X-ray diffraction data indicate a new phase of H 2 SO 4 molecules surrounding the tubes as cylindrical shells. 2 We show here that the SWNT/H 2 SO 4 interaction also induces short-range orientational order 3 which templates the crystallization of free acid with specific orientations.…”

Charge transfer between carbon nanotubes and sulfuric acid as determined by Raman spectroscopy

“…4 Protonation and formation of layers around the nanotubes has been experimentally observed. [10][11][12][13][14] So far the Raman shift due to charge transfer has been deduced through electrochemical measurements using 320 f C in cm −1 (Ref. 4).…”

Nanoscale pressure effects in individual double-wall carbon nanotubes

“…Consequently, the pressure is transmitted less effectively in the case of oxygen and alcohol due to the structure formed around the tube by the first few layers. Evidence of H 2 SO 4 partly ordered around CNTs has been recently reported 34 and the formation of structured water and other species has been considered. 33 In this paper, we present for the first time clear experimental results which show that surface interaction effects at the nanometric scale can lead to a change of up to 50% in the stress transmission using DWCNTs.…”