Importance of carbon solubility and wetting properties of nickel nanoparticles for single wall nanotube growth

TL;DR

This study uses atomistic simulations to explore how nickel nanoparticle properties, especially carbon solubility and wetting behavior, influence the growth of single wall carbon nanotubes, highlighting their critical role in catalyst performance.

Contribution

It provides new insights into how carbon solubility and wetting properties of nickel nanoparticles affect nanotube growth, using atomistic and Monte Carlo simulations.

Findings

Carbon solubility increases in smaller, molten nickel nanoparticles.

Higher carbon content promotes dewetting of Ni nanoparticles from carbon walls.

Wetting properties are crucial for enabling nanotube growth.

Abstract

Optimized growth of Single Wall Carbon Nanotubes requires a full knowledge of the actual state of the catalyst nanoparticle and its interface with the tube. Using Tight Binding based atomistic computer simulations, we calculate carbon adsorption isotherms on nanoparticles of nickel, a typical catalyst, and show that carbon solubility increases for smaller nanoparticles that are either molten or surface molten under experimental conditions. Increasing carbon content favors the dewetting of Ni nanoparticles with respect to sp2 carbon walls, a necessary property to limit catalyst encapsulation and deactivation. Grand Canonical Monte Carlo simulations of the growth of tube embryos show that wetting properties of the nanoparticles, controlled by carbon solubility, are of fundamental importance to enable the growth, shedding a new light on the growth mechanisms.