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

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.