Electrical properties of hierarchical nitrogen-doped multi-walled carbon nanotubes obtained using cobalt nanoparticles

In this work, for the first time, both initial and secondary branches of hierarchical nitrogen-doped multi-walled carbon nanotubes (h-N-MWCNTs) were obtained using chemical vapor deposition due to the decomposition of ace-tonitrile over Co-based nanoparticles. The results of a study of the electrical conductivity of h-N-MWCNTs for a wide temperature range of 300-4.2 K are presented. It was shown that fluctuation-assisted tunneling between delocalized states is the dominant conduction mechanism at temperatures above 50 K. An analysis of the temperature and electric field dependences of the resistance indicates that the transfer of electric charges below 50 K occurs due to hoppings between localized states located in the vicinity of the Fermi level. It was shown that the Coulomb interaction affects the charge carrier transport. The width of the Coulomb gap estimated from the temperature dependence of the resistance is 0.5 meV. The electrical conductivity of h-N-MWCNTs in the temperature range of 50-4.2 K occurs by the Efros-Shklovskii variable range hopping conduction mechanism. It was found that the charge localization length is approximate to 150 nm. Electrical property analysis indicates that the dielectric constant of the h-N-MWCNTs is approximate to 100.