Published online by Cambridge University Press: 31 January 2011
The effect of nonsupported MoO3 as a conditioning catalyst on the preparation of carbon nanotubes (CNTs) using a common main catalyst Fe/MgO was investigated. Without using MoO3, only single-walled CNTs were produced at low yield. In contrast, the use of MoO3 provided single-walled and double-walled CNTs at high yield. The MoO3 conditioning catalyst enhances not only the yield but also the diameter and layer number of CNTs. The higher yield formation of more layered CNTs with larger diameter would be attributed to the preproduction of reactive hydrocarbon species by the conditioning catalyst and their growth to larger molecular-weight reactive species.