Catalyst-substrate interaction governs SWCNT nucleation and cap lift-off: insights from molecular dynamics simulation

Nucleation is a pivotal stage in dictating the structure and properties of carbon nanotubes (CNTs) and has historically been a central focus in studies of their synthesis mechanisms. Particularly after the formation of a graphene cap, the atomic-scale competition between catalyst encapsulation and cap lift-off directly determines whether single-walled carbon nanotubes (SWCNTs) can successfully grow. However, systematically elucidating and precisely controlling the dynamic mechanism of this competition remains challenging. This study selects nickel (Ni) nanoparticles as the catalyst system and employs reactive force field molecular dynamics (ReaxFF MD) simulations to systematically and deeply investigate the growth dynamics of SWCNTs and the cap lift-off mechanism. This study reveals the significant influence of catalyst/substrate interaction strength on the structural evolution of the carbon cap and its lift-off. Based on these findings and the principle of system energy minimization, a dynamic theoretical model is proposed to describe catalyst periodic dynamic restructuring and cap/catalyst interactions during the nucleation process, which provides the new theoretical guidance for the future precise control of SWCNT synthesis and their structural integrity.

Graphical abstract