▎ 摘　　要

Graphene synthesis at lower temperatures is quite important for a wider range of practical applications. Sn, which is recently found as a promising catalyst for the low-temperature graphene growth, is taken as the study material in this work. Based on the detailed transmission electron microscopy (TEM) observation, we found that catalytic activity of Sn nano-particles is highly temperature dependent which was observed during graphitization of amorphous carbon. For this study, C-Sn composite nanofibers were prepared on an edge of a carbon foil by the Ar+ ion irradiation with simultaneous supply of Sn. As-fabricated C-Sn composite nanofibers were observed to be the amorphous C nanofibers (CNFs) in which the Sn nanoparticles dispersed. The as-prepared samples were annealed at 180-250 degrees C in a vacuum and were characterized using Raman spectra and high-resolution TEM to study the graphitization process. The graphitization started to occur at an annealing temperature of 180 degrees C, which is much lower than the graphitization temperature for bulky Sn. Based on the detailed TEM observation of annealed samples, a model to explain the graphitization mechanism at such a low temperature was proposed.