The evolution mechanism of Mo catalyst at the initial stage of catalytic growth of single-walled carbon nanotubes.

Molybdenum (Mo) nanoparticles (NPs) are one of the most effective refractory catalysts for preparing single-walled carbon nanotubes (SWCNTs) with high chirality. In this work, the evolution of Mo NPs at the initial stage of catalytic growth of SWCNT was investigated. It was found that NPs underwent transformation between the solid and semi-liquid phases during gradual deposition of C atoms, even though the deposition temperature was far below the melting point of NPs. Such transformation was caused by the elastic strain in NPs that could be manipulated by carbon (C) atoms. Furthermore, the results indicated that the lifetime of NPs in the semi-liquid state could be controlled by adjusting the feeding rate of C atoms. This work not only provides useful insight into the evolution of Mo NPs during the early stage of the catalytic growth of SWCNTs, but also opens up new prospects for controlling the lifetime of NPs in the semi-liquid phase by changing the experimental parameters. [Display omitted] [ABSTRACT FROM AUTHOR]