Unifying catalyst size dependencies in floating catalyst and supported catalyst carbon nanotube synthesis

Abstract Detailed studies with floating catalyst systems, namely, laser evaporation and laser assisted chemical vapour deposition (CVD), enabled the development of a catalyst volume to surface area model which dictates if a single walled carbon nanotube (SWCNT) can emerge or not. The model predicts differences in the case of supported catalysts. It predicts multi‐walled carbon nanotubes (MWCNT) will also emerge. This difference arises due to the catalyst/support interaction. Further, the model says that for supported catalysts the catalyst volume to surface area ratio also regulates the tube diameter and the number of walls the nanotube will have. In this contribution, experimental CVD data using predefined catalyst particles on a support are presented and compared with floating catalyst data. The findings for supported catalysts are in full agreement with those predicted by the catalyst surface area to volume model. The data show unified catalyst size dependencies for floating catalyst and supported catalyst carbon nanotube synthesis routes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)