In situ Observations of Catalyst Dynamics during Surface-Bound Carbon Nanotube Nucleation

TLDR

The study aims to observe surface‑bound catalytic CVD of single‑walled carbon nanotubes and nanofibers at atomic scale. Atomic‑scale, video‑rate environmental TEM and time‑resolved XPS are employed to capture the process. We observe that catalyst nanoparticles on SiOx are crystalline and highly deformable during nanotube formation; a single‑walled CNT nucleates by lift‑off of a carbon cap, while cap stabilization and growth involve dynamic reshaping of the catalyst nanocrystal, and for nanofibers, graphene layer stacking is governed by successive elongation and contraction of the catalyst tip.

Abstract

We present atomic-scale, video-rate environmental transmission electron microscopy and in situ time-resolved X-ray photoelectron spectroscopy of surface-bound catalytic chemical vapor deposition of single-walled carbon nanotubes and nanofibers. We observe that transition metal catalyst nanoparticles on SiOx support show crystalline lattice fringe contrast and high deformability before and during nanotube formation. A single-walled carbon nanotube nucleates by lift-off of a carbon cap. Cap stabilization and nanotube growth involve the dynamic reshaping of the catalyst nanocrystal itself. For a carbon nanofiber, the graphene layer stacking is determined by the successive elongation and contraction of the catalyst nanoparticle at its tip.