Effects of the Fe-Co interaction on the growth of multiwall carbon nanotubes

The influences of active species Fe-Co composition on the growth of carbon nanotubes (CNTs) were systemically investigated. CNTs were grown from the pyrolytic decomposition of C2H2 over Fe-Co/CaCO3 catalysts by radio frequency chemical vapor deposition (CVD). The catalyst stoichiometry was found to strongly influence the carbon deposition rate as well as the nanotube crystallinity characteristics. Compared to the CNTs synthesized over the Co/CaCO3 catalyst, those produced by Fe-containing catalysts have less amorphous carbon. The maximum yield of high-quality CNTs was achieved at the Fe/Co atomic ratio of 2:1 due to a suitable concentration of benzene generated from acetylene CVD on such catalytic system. Fe and Co can form alloy and therefore the d-electron interaction between Fe and Co was believed to play an important role in the CNT growth. (C) 2008 American Institute of Physics.