Predicting whether aromatic molecules would prefer to enter a carbon nanotube: A density functional theory study

Area of Science:

• Computational Chemistry
• Materials Science
• Nanotechnology

Background:

• Carbon nanotubes (CNTs) are versatile nanomaterials with unique electronic and structural properties.
• Understanding the adsorption behavior of aromatic molecules on CNTs is crucial for applications in sensing, drug delivery, and catalysis.
• Aromatic molecules, including aniline, benzophenone, and diphenylamine, are prevalent in various chemical and biological systems.

Purpose of the Study:

• To investigate the interaction and binding energies between CNTs and selected aromatic molecules.
• To determine the preferred adsorption site (inner vs. outer surface) of aromatic molecules on CNTs.
• To explore the influence of molecular structure and surface curvature on adsorption stability.

Main Methods:

• Density Functional Theory (DFT) calculations using the B3LYP-D3 functional were employed.
• Simulations were performed on CNTs of varying lengths (4-CNT, 6-CNT, 8-CNT) to model interactions.
• Intermolecular binding and adsorption energies were computed to quantify interaction strength.

Main Results:

• All studied aromatic molecules exhibited strong intermolecular binding energies with the inner surface of CNTs.
• Hydrogen bonding between aromatic molecules containing N and O atoms significantly enhanced adsorption stability.
• Aromatic molecules were predicted to preferentially enter the CNT when multiple molecules interacted simultaneously.
• Adsorption energy on graphene increased with surface concavity, indicating enhanced binding on curved surfaces.

Conclusions:

• The inner surface of CNTs provides a favorable site for the adsorption of aromatic molecules.
• Intermolecular interactions, particularly hydrogen bonding, play a critical role in stabilizing adsorption within CNTs.
• Surface curvature, as observed in graphene, positively correlates with binding energy, suggesting enhanced interactions with concave structures.