Synthesis of single-walled carbon nanotubes using binary (Fe, Co, Ni) alloy nanoparticles prepared in situ by the reduction of oxide solid solutions

Passing a H2–CH4 mixture over oxide spinels containing two transition elements as in Mg0.8MyM′zAl2O4 (M, M′=Fe, Co or Ni, y+z=0.2) at 1070°C produces small alloy nanoparticles which enable the formation of carbon nanotubes. Surface area measurements are found to be useful for assessing the yield and quality of the nanotubes. Good-quality single-walled nanotubes (SWNTs) have been obtained in high yields with the FeCo alloy nanoparticles, as evidenced by transmission electron microscope images and surface area measurements. The diameter of the SWNTs is in the 0.8–5 nm range, and the multiwalled nanotubes, found occasionally, possess very few graphite layers.