Molecular Dynamics of the Nucleation Mechanism of Fe₅₅Mo_n (n = 1–50) Alloy Nanoparticles for the Catalytic Growth of Single-Walled Carbon Nanotubes

Abstract

Inhibiting the aggregation of nanoparticles (NPs) to prepare catalysts with a uniform particle size is crucial to control the chirality of single-walled carbon nanotubes (SWCNTs). It has been proven that the quality of SWCNTs can be effectively improved through the use of FeMo NPs with small fractions of Mo. In this work, the nucleation mechanism of FeMo NPs, in which Mo atoms are gradually deposited on the solid-phase Fe 55 seeds, is studied via classical molecular dynamics. The results demonstrate that the difference in cohesive energies between the components acts as a driving force for the transformation of FeMo NPs from the solid to the semiliquid phase. Furthermore, the lifetime of the alloy NPs in the semiliquid phase can be controlled by adjusting the Mo feeding rate. This study not only enables one to gain insight into the nucleation mechanism of FeMo NPs but also provides a strategy for restraining the structural fluctuation of NPs in the preparation of alloys with uniform particle size through adjusting the experimental parameters.