Nitrogen ion casting on vertically aligned carbon nanotubes: Tip and sidewall chemical modification

Controlling pyridinic, pyrrolic, graphitic, and molecular nitrogen in multi-wall carbon nanotubes using precursors with different N/C ratios in aerosol assisted chemical vapor deposition

“…[14][15][16][17] The most common forms of embedded nitrogen discussed in the literature are graphitic, pyridinic and pyrrolic nitrogen. 1,[18][19][20] Graphitic nitrogen refers to a nitrogen atom with three carbon neighbours in a hexagonal lattice, if the nitrogen is two-fold coordinated similar to that is found in pyridine, it is called pyridinic, and three-fold coordinated nitrogen in a region of defective non-aromatic lattice is associated with pyrrolic nitrogen. While the majority of reports argue that, due to their different stabilities, the concentration of these different types of nitrogen atoms in N-MWCNTs is largely controlled by the synthesis temperature 21,22 some accounts also consider the nature of the precursor to be a crucial factor.…”

Changes of the electronic structure of the atoms of nitrogen in nitrogen-doped multiwalled carbon nanotubes under the influence of pulsed ion radiation

“…Note that the local maximum at the energy of $401 eV can be deconvoluted with one component, but FWHM of the peak in this case will be significantly greater than for other components, which indicates the need for its deconvolution into several components. Spectrum component N4, located on the energy 404 ± 0.2 eV, according to the literature data, is associated with NO groups (usually, pyridine oxide) or with physisorbed nitrogen [9,27]. Component N5 with a binding energy 405.1 ± 0.2 eV corresponds to molecular nitrogen which is intercalated inside the cavities of the nanotubes, as well as between the graphene layers during the synthesis of CN x -MWCNTs [2,10].…”

“…2b), the N 1s spectrum can be deconvoluted into five components: N1, N2, N3, N4, N5. Spectrum component N1 at the binding energy 398.7 ± 0.2 eV corresponds to nitrogen in the pyridinic configuration [2,[5][6][7]9]. In pyridine-like defects of the graphene structure of the nanotubes two electrons of nitrogen are involved in r-bonds with neighboring carbon atoms, one electron contributes to the p-system of CN x -MWCNTs, and two electrons form a pair localized around the nitrogen atom.…”

“…In pyridine-like defects of the graphene structure of the nanotubes two electrons of nitrogen are involved in r-bonds with neighboring carbon atoms, one electron contributes to the p-system of CN x -MWCNTs, and two electrons form a pair localized around the nitrogen atom. Peak N2 at the energy 400.3 ± 0.2 eV corresponds to nitrogen atoms in the pyrrolic configuration [2,9]. In this configuration three electrons of nitrogen form r-bonds with carbon, and the remaining two fill p-states.…”

“…Quantitative nitrogen content in these chemical states has different effects on the electronic structure CN x -MWCNTs. It is possible to change directionally the chemical state of nitrogen atoms in CN x nanotubes, for example, via controlling growth parameters using different variations of the process CVD [8][9][10], as well as using post-synthesis processing (annealing in air [11]/in inert environment [11,12], in acids [11,13], ozonation [14]). Wide possibilities for modifying the properties of MWCNTs arise when using a pulsed ion beam of high power density [15].…”