First principles study on the boron–nitrogen domains segregated within (5, 5) and (8, 0) single-wall carbon nanotubes: Formation energy, electronic structure and reactivity

The geometries, formation, cohesive energies, electronic properties and reactivity of pristine and boron–nitrogen (BN) co-doped (5, 5) and (8, 0) single-wall carbon nanotubes (SWNTs) are investigated using density functional calculations. There is a strong tendency for the formation of segregated BN domains within SWNTs and the formation and cohesive energy values increase with increase in number of BN domains, the values intermediate between pristine SWNT and BNNT. Moreover, BN co-doped SWNTs with B excess or N excess impurity exhibits the characteristics of a donor or acceptor as the electronic states are influenced by number of occupied states in the valence and conduction bands. Inclusion of BN domains in (5, 5) SWNT exhibits a metallic to semiconductor transition, whereas for (8, 0) SWNT, further opening of the band gap is observed with increase in BN domain size. The wavefunction plots at the Γ point show the localization of electronic states around BN domain region.