Controlling the growth of single-walled carbon nanotubes on surfaces using metal and non-metal catalysts

Thanks to the development of controlled synthesis techniques, carbon nanotubes, a 20-year-old material, are doing better at finding practical applications. The history of carbon nanotube growth with controlled structure is reviewed. There have been two main categories of catalysts used for carbon nanotube growth, metal and non-metal. For the metal catalysts, the growth process and the mechanism involved have been adequately discussed, with a widely accepted vapor-liquid-solid growth mechanism. The strategies for preparing single-walled carbon nanotube samples with well-defined structures such as geometry, length and diameter, electronic property, and chirality have been well developed based on the proposed mechanism. However, a clear mechanism is still being explored for non-metal catalysts with a hypothesis of a vapor-solid growth mechanism. Accordingly, the controlled growth of carbon nanotubes with a non-metal catalyst is still in its infancy. This review highlights the structure-control growth approach for carbon nanotubes using both metal and non-metal catalysts, and tries to give a full understanding of the possible growth mechanisms. (C) 2012 Elsevier Ltd. All rights reserved.