Understanding the nucleation mechanisms of Carbon Nanotubes in catalytic Chemical Vapor Deposition

TL;DR

This study investigates how carbon nanotubes nucleate on nickel catalysts during chemical vapor deposition, emphasizing the role of surface carbon concentration and catalyst state in the nucleation process.

Contribution

It introduces a computational approach combining tight binding models and Monte Carlo simulations to analyze nucleation mechanisms in CNT growth.

Findings

Nucleation occurs within a specific carbon chemical potential range.

Surface carbon concentration is critical for nucleation.

Catalyst initial state influences carbon solubility and nucleation.

Abstract

The nucleation of carbon caps on small nickel clusters is studied using a tight binding model coupled to grand canonical Monte Carlo simulations. It takes place in a well defined carbon chemical potential range, when a critical concentration of surface carbon atoms is reached. The solubility of carbon in the outermost Ni layers, that depends on the initial, crystalline or disordered, state of the catalyst and on the thermodynamic conditions, is therefore a key quantity to control the nucleation.