Synthesis of high purity multiwalled carbon nanotubes over Co-Mo/ MgO catalyst by the catalytic chemical vapor deposition of methane

Nearly uniform diameter multiwalled carbon nanotubes (MWCNTs) were synthesized over a magnesia supported Co-Mo bimetallic catalyst through the catalytic chemical vapor deposition of methane. The bimetallic catalyst with a composition of Co∶Mo∶MgO=5∶20∶75 (mass ratio) was prepared by a sol-gel method. Thermagravimetric analysis shows that MWCNTs were synthesized in high yield. The selectivity of the catalyst for MWCNTs over undesired amorphous carbon was 91.17%. Transmission electron microscopy indicates that the MWCNTs grown on the catalyst have an average diameter of 6.2±0.5nm (mean±standard deviation). Through simple purification by mild acid treatment, the catalyst residue for the purified samples was reduced to 0.72%.