$N_2$ adsorption on the inside and outside the single-walled carbon nanotubes by density functional theory study
The adsorption energies, bond order, atomic charge, optical properties, and electrostatic potential of nitrogen molecules of armchair single-walled carbon nanotubes (SWCNTs) and nitrogen-doped single-walled carbon nanotubes (N-SWCNTs) were investigated using density functional theory (DFT). Our results show that adsorption of the $N_2$ molecules on the external wall of a nanotube is more effective than on the internal wall in SWCNTs. The results show that $N_2$ molecule(s) are weakly bonded to SWCNTs and N-SWCNTs through van der Waals-type interactions. The interaction of $N_2$ molecules with SWCNTs and N-SWCNTs is physisorption as the adsorption energy and charge transfer are small, and adsorption distance is large. The electronic transitions from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) (H → L) have the maximum wavelength and the lowest oscillator strength. The potential sensor on the surface of pristine SWCNTs and N-SWCNTs for the adsorption of $N_2$ molecule(s) is investigated. The N-loaded single-walled carbon nanotube is introduced as a better $N_2$ molecule(s) detector when compared with SWCNTs.
Volume 96, 2022
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