Morphological stabilization, destabilization, and open-end closure during carbon nanotube growth mediated by surface...

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Carbon nanotubes (CNTs) are crucial nanomaterials with diverse applications.
• Understanding CNT growth mechanisms is essential for controlling their structure and properties.
• Surface diffusion plays a key role in the kinetics of CNT formation.

Purpose of the Study:

• To investigate the role of surface diffusion in the growth stability of open-ended carbon nanotubes.
• To elucidate the mechanisms of nanotube destabilization and end closure.
• To explore the influence of kinetic effects on single-wall versus multi-wall CNT formation.

Main Methods:

• Theoretical analysis of growth kinetics at the nanotube edge.
• Modeling the competition between hexagon and pentagon formation.
• Investigating the impact of surface diffusion flux on growth stability.
• Analyzing the transition from single-wall to multi-wall growth.

Main Results:

• Nanotube growth stability is mediated by surface diffusion on the lateral surface.
• End closure occurs when surface diffusion flux decreases, favoring pentagon formation over hexagon formation.
• Kinetic effects, specifically the ratio of atom arrival time to pentagon formation time, dictate growth termination.
• Surface diffusion also influences the transition between single-wall and multi-wall nanotube growth.
• Diffusion from behind the growth interface stabilizes the open edge morphology.

Conclusions:

• Surface diffusion is a critical factor in controlling carbon nanotube growth stability and morphology.
• Growth conditions that reduce surface diffusion flux can lead to nanotube end closure.
• The interplay of kinetic processes at the growth edge determines whether single-wall or multi-wall nanotubes are formed.