Effect of B/N co-doping on the stability and electronic structure of single-walled carbon nanotubes by first-principles theory

Abstract

The stability and electronic structure of single-walled carbon nanotubes with B/N co-doping are investigated in detail by using the first-principles theory. From eight possible B/N co-doping configurations, it is found that the one with substitutional B and N atoms located at neighboring sites has a smaller formation energy than that with separate B/N atoms. The electronic structure of armchair carbon nanotubes evolves from metallic to semiconducting as a result of B/N co-doping, whereas the energy gaps of the intrinsically semiconducting nanotubes are reduced significantly. In contrast, the small zigzag nanotubes always remain metallic properties due to their large curvature effects except (5, 0) after B/N co-doping. As the atomic concentration of B/N co-doping is increased, the energy gaps of carbon nanotubes oscillate around a constant level, which is much lower than the energy gap of BC(2)N nanotubes. Moreover, the B/N co-doped carbon nanotubes with B- or N-rich impurities exhibit the characteristics of an acceptor or donor, respectively, since their electronic structures are significantly influenced by the occupied states in the valence and conduction bands due to the shifting of the Fermi level.

A Cu-atom-chain current channel with a width of approximately 0.246 nm on (5, 0) single-wall carbon nanotube

“…The stability of the Cu-chain-SWCNT was evaluated by calculating the formation energy ( E f ), which is defined by the following equation 35 , 36 : where E dop and E SWCNT is the total energy of the Cu-chain-SWCNT and pristine SWCNT, respectively; μ (Cu) is the chemical potential of a Cu atom, calculated from the isolated Cu atom (in a 20 × 20 × 20 Å lattice) using DMOL 3 code 37 ; n(C) and n(Cu) are the number of C atoms in the pristine SWCNT and Cu atoms in the Cu-chain-SWCNT, respectively. The stability of doped SWCNT can be evaluated using the formation energy; the more negative the formation energy, the more stable they should be 35 , 37 – 39 . The calculated E f of the Cu-chain-SWCNT is −0.325 eV/atom, indicating that the Cu-chain-SWCNT is energetically favorable.…”

Novel structure and abnormal electronic properties of ultra-thin BC2N nanotubes from first-principles investigation

“…where E tot is the total energy of the BC 2 N nanotubes; (B), (C), and (N) are the chemical potential of single B, C, and N atoms obtained by calculating the total energy per atom of ␣-boron phases, single free carbon atom and ␣-nitrogen phases [43], respectively; n(B), n(C), and n(N) are the number of B, C, and N atoms in BC 2 N nanotubes, respectively. …”

“…We defined two different styles of bond for zigzag and armchair nanotubes. As shown in Figure 3, ⊥ represents the bond that perpendicular to the tube axis, represents the bond that parallel to the tube axis (the method has been employed in previous paper [43]). For BC 2 N nanotubes ZZ-d and ZZ-e, the average bond length of C B⊥ and B N⊥ became larger than C C⊥ and C N⊥ obviously, resulting in tube ZZ-d has an oval cross section and the structure of tube ZZ-e was also changed slightly.…”

The recent advancement of low-dimensional nanostructured materials for drug delivery and drug sensing application: A brief review

“…N. Saikia et al proposed SWCNT as a drug carrier to the target area [ 182 ]. As the Si doping in the CNT is less reported in the literature than the B/N doping, better electronic properties of Si lead them to use Si-doped SWCNT to carry the INH drug using DFT theory and molecular docking [ 84 , 183 ]. In a Van der Waals interaction corrected investigation it was found that INH parallel to the (5, 5) SWCNT have better stability with more adsorption energy of 15.59 kcal/mol compared to the perpendicular alignment of the INH with (5, 5) SWCNT with an adsorption energy of 13.65 kcal/mol.…”