Experimental and theoretical studies on the structure of N-doped carbon nanotubes: Possibility of intercalated molecular N2

Abstract

The concentration distribution and electronic structure of N atoms doped in multiwalled banboo-like carbon nanotubes (CNTs) are examined by photon energy-dependent x-ray photoelectron spectroscopy and x-ray absorption near edge structure. The inner part of the nanotube wall has a higher N concentration and contains molecular N2 presumably intercalated between the graphite layers. These results are supported by the self-consistent charge-density-functional-based tight-binding calculation of double-walled CNTs, showing that the intercalation of N2 is energetically possible and the graphite-like N structure conformer becomes more stable when the inner wall is more heavily doped.

FTIR studies of nitrogen doped carbon nanotubes

“…Out of the above identified bonds, the presence of C -N and N-CH 3 bonds at 1250 and 1372 cm À 1 is most interesting. The strong peaks at 1250 and 1372 cm À 1 are consistent with C -N and N -CH 3 stretching vibrations attributed by Choi et al [14] to the presence of intercalated N atoms between the graphite layers at the inner part of the nanotube walls. However, in our opinion the intercalated nitrogen atoms in between the graphite walls may not be strongly IR active.…”

Hydrogen adsorption of novel N-doped carbon nanotubes functionalized with Scandium

“…These is usually done in the presence of catalysts or iron oxides in practice. Sufficient energies to form 3NV and 4ND in N-doped carbon nanotubes are provided with relatively high synthesis temperature of 700e900 C using nitrogen-rich precursors for CVD processes [24] and [25] along with the use of catalysts, though the formation energies of 3NV defects are higher than sp 2 -substitution and 4ND defects. Hirshfeld population analysis shows that charge of the order 0.116 e on each of the 4 N atoms of 4ND-CN x NT, hence this site can act as a strong oxidizing agent for TMs due to its reactivity.…”

Nitrogen‐Doped Carbon Nanotubes as a Highly Active Metal‐Free Catalyst for Selective Oxidation

“…The results of statisti- The N 1s X-ray photoelectron spectrum (XPS) recorded on the N-CNTs that contain 2.6 at % of nitrogen (N-CNT 2.6N ) is presented in Figure 3 A and shows the presence of several nitrogen-bonded carbon species: pyridinic, pyrrolic, quaternary, and an oxidized type of pyridinic nitrogen. [35][36][37][38][39][40] Among these different species, the pyridinic nitrogen with a localized electron lone pair seems to be the most important for catalysis. The absence of iron particles on the surface of the N-CNTs was also investigated by using XPS.…”