Bamboo-shaped carbon nanotubes produced by catalytic decomposition of methane over nickel nanoparticles supported on aluminum

Bamboo-shaped carbon nanotubes (CNTs) and herringbone nanofibers were catalytically synthesized by a decomposition of methane over Ni/Al catalyst under N-2 at the low temperature (500-600 degrees C). Transmission electron microscopy (TEM) was used to investigate the bamboo-shaped CNTs and the nanofibers. High-resolution TEM analysis revealed that two species of bamboo-shaped tubes with different morphologies and structures, categorized according to the shape and participation of the encapsulated catalytic nanoparticles, coexist in one sample. It is found that the morphology and structure of the catalytic particles play very important roles during carbon nanomaterial growth. The growth mechanisms for the bamboo-shaped CNTs and nanofibers are proposed in detail, especially the formation process of compartments of the bamboo-shaped CNTs. (c) 2006 Elsevier B.V. All rights reserved.