This is due to higher ionization energy of nitrogen atom compared to carbon and boron. The calculated ĪS,max values of the NB7, NC6 and NC8 models are 7.7, 7.5 and 7.5 eV, respectively.Such a different reactivity pattern between the BC3NT doped at boron and carbon sites can be attributed to the different contribution of electron pair of N atom to form a delocalized conjugated system with the adjacent sp2 -hybridized network.