Transforming carbon nanotubes by silylation: an ab initio study

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Carbon nanotubes and graphene are advanced carbon nanostructures with unique electronic properties.
• Chemical functionalization is key to tailoring their properties for specific applications.
• Understanding the interaction of radicals with these materials is crucial for developing new functionalization strategies.

Purpose of the Study:

• To investigate the chemical functionalization of single-wall carbon nanotubes and graphene using silyl (SiH3) radicals and hydrogen.
• To determine the nature of bonding and structural changes induced by silylation.
• To explore the impact of silylation on the electronic and vibrational properties of these nanostructures.

Main Methods:

• Utilizing ab initio density functional theory (DFT) calculations.
• Simulating the interaction of silyl radicals and hydrogen with graphene and carbon nanotube models.
• Analyzing structural relaxations, electronic structure changes (sp3 hybridization), and vibrational spectra.

Main Results:

• Silyl radicals form strong covalent bonds with both graphene and carbon nanotube walls.
• Silylation induces local structural distortions, increasing the sp3 character of the carbon atoms.
• All studied carbon nanotubes become semiconductors after silylation, irrespective of their initial chirality.
• Calculated vibrational spectra show distinct frequency shifts indicative of successful silylation.

Conclusions:

• Silylation is an effective method for covalently functionalizing graphene and carbon nanotubes.
• The process fundamentally alters the electronic properties, converting all carbon nanotubes to semiconductors.
• Vibrational spectroscopy can serve as a diagnostic tool to confirm successful silylation of these nanostructures.