High-yield synthesis of bundles of double- and triple-walled carbon nanotubes on aluminum flakes

Abstract

High-quality double- and triple-walled carbon nanotubes have been synthesized using Fe−Co catalysts supported on aluminum flake powder. The diameters and lengths of the obtained nanotubes are in the ranges of 3–8 nm and 150–300 μm, respectively, and the specific surface area were quoted as 600 m2/g. The yield of the nanotubes synthesis relative to the initial weight of the catalyst is in the order of 1200%, with 70% of the resulting material consisting of thin carbon nanotubes with less than 6 nm of outer diameter and carbon purity of greater than 90%. Our results indicate that the use of aluminum as catalyst support have a profound effect in the formation of the metal nanoparticles. In addition to boost the reduction the catalyst precursors, the high chemical reactivity of metallic aluminum drives the thermal formation of an oxide layer on the Al surface that suppresses the diffusion and aggregation of catalyst nanoparticles. As a result, a simple impregnation method can be adopted to produce catalyst nanoparticles with narrow size distribution that are suitable for the growth of few wall carbon nanotubes at high yield and large scale.