EFFECT OF STRUCTURE AND SURFACE STATE OF NITROGEN DOPED CARBON NANOTUBES ON THEIR FUNCTIONAL AND CATALYTIC PROPERTIES

A comprehensive study of nitrogen doped carbon nanotubes (N–CNTs) with nitrogen content varying from 0 at.% to 7.3 at.% is reported. A correlation is revealed between the content of pyridine-like nitrogen and the defectivity of the N–CNT bamboo-like structure. A model of graphene layer with defects containing ordered carbon vacancies and pyridine nitrogen is proposed. The model is based on a combination of experimental data obtained by powder X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy and simulation of the N–CNT structure by the use of g-C3N4 structural elements. It is shown that more than a two-fold increase of the N–CNT specific capacity in acidic and alkaline electrolytes compared to that of undoped carbon nanotubes is due to the fact that N–CNTs posses significantly better hydrophilic properties due to the defects based on pyridine-like nitrogen centers. The N–CNT efficiency as a catalyst and a palladium catalyst support in the reaction of oxidative desulfurization of dibenzothiophene is demonstrated.