Shape-Controlled Growth of Carbon Nanostructures: Yield and Mechanism.

Carbon nanostructures with precisely controlled shapes are difficult materials to synthesize. A facet-selective-catalytic process was thus proposed to synthesize polymer-linked carbon nanostructures with different shapes, covering straight carbon nanofiber, carbon nano Y-junction, carbon nano-hexapus, and carbon nano-octopus. A thermal chemical vapor deposition process was applied to grow these multi-branched carbon nanostructures at temperatures lower than 350 °C. Cu nanoparticles were utilized as the catalyst and acetylene as the reaction gas. The growth of those multi-branched nanostructures was realized through the selective growth of polymer-like sheets on certain indexed facets of Cu catalyst. The vapor-facet-solid (VFS) mechanism, a new growth mode, has been proposed to interpret such a growth in the steps of formation, diffusion, and coupling of carbon-containing oligomers, as well as their final precipitation to form nanostructures on the selective Cu facets.