Carbon nanotube synthesis in a flame using laser ablation for in situ catalyst generation

Abstract

Laser ablation of either Ni or Fe is used to create nanoparticles within a reactive flame environment for catalysis of carbon nanotubes (CNTs). Ablation of Fe in a CO-enriched flame produces single-walled nanotubes, whereas, ablation of Ni in an acetylene-enriched flame produces carbon nanofibers. These results illustrate that the materials for catalyst particle formation and CNT, SWNT or nanofiber, inception and growth in the aerosol phase can be supplied from separate sources; a metal-carbon mixture produced by condensation is not necessary. Both particle formation and CNT inception can begin from molecular species in a laser-ablation approach within the complex chemical environment of a flame. Moreover, SWNTs and nanofibers can be synthesized within very short timescales, of the order of tens of milliseconds. Finally, high-intensity pulsed laser light can destroy CNTs through either vaporization or coalescence induced by melting.