A comparative study of the electronic structures of oxygen- and chlorine-treated nitrogenated carbon nanotubes by x-ray absorption and scanning photoelectron microscopy

The electronic structures and bonding properties of oxygen- and chlorine-treated nitrogenated carbon nanotubes (N-CNTs) were studied using x-ray absorption near-edge structure (XANES) and scanning photoelectron microscopy. Features in the C $K$-edge XANES spectra are shifted by $∼0.3eV$ toward higher energies and by $∼1.1eV$ toward lower energies relatively to those of the more symmetrical pyridinelike and graphitelike structured N-CNTs upon chlorination and oxidation, respectively. Increases in N $K$-edge XANES intensities for both chlorination and oxidation reveal substitution of C–C bonds by C–N bonds consistent with the observed valence-band photoemission spectra of the decrease of the C $2s$ bond and the increase of the N $2s$ bond.