# Quantum Chemical Studies on the Structural, Electronic, and Vibrational Properties of Boron Carbonitride Nanotubes

## TL;DR

This paper studies the properties of boron carbonitride nanotubes using quantum chemistry to explore their structure, electronic behavior, and potential applications.

## Contribution

The study reveals how nanotube length affects electronic and solubility properties, enabling fine-tuning for nanoscale applications.

## Key findings

- Longer BC2N nanotubes exhibit increased electrophilic character and improved solubility in water.
- Semiconductor-to-semimetallic transitions occur with increasing nanotube length, affecting conductivity.
- Molecular electrostatic potential maps indicate regioselective reactivity potential for BC2N nanotubes.

## Abstract

The structural, vibrational, and electronic properties
of zigzag
(n, 0) BC2N nanotubes are
investigated in their most stable configuration, type IV. Studies
are based on density functional theory (DFT) using the M06-2X/6-31G(d)
level of theory. The property–structure relationship is investigated
by focusing on the chirality index (n). Furthermore, to analyze the length dependence of the stability/reactivity
of BC2N nanotubes, short (n = 5–14, s-BC2NNTs) and long (n = 5–13, l-BC2NNTs) nanotubes
were proposed, with average lengths of 18.07 and 26.74 Å, respectively.
Total energy minimization, assuming nonmagnetic nature and charge
neutrality, yielded the ground state of all nanostructures. Results
show that the electrophilicity and nucleophilicity indices exhibit
that the BC2NNTs are electrophilic systems; however, an
increase in the length of the nanotube triples its electrophilic character.
The s-BC2NNTs show a semiconductor
character, while l-BC2NNTs
show a semiconductor-to-semimetallic character; therefore, the length
of the nanotube is a key element for fine-tuning the conductive properties
of these systems. Nanotubes of larger length and diameter are favored,
based on analysis of cohesion energies. Furthermore, a longer axial
length of the nanotube improves the solubility properties as it considerably
increases the dipole moment and the solvation energy in water. Finally,
BC2NNTs showed polarization relative to the distribution
of negative and positive charges, as indicated by molecular electrostatic
potential maps. This is important for possible regioselective reactions.
The set of BC2NNTs studied in this work may be proposed
for biological applications. Also, due to the molecular gap energy
found in the range 0.35 < Eg < 1.6
eV, we propose that these structures could be applied in the fabrication
of integrated circuits at the nanoscale.