Growth of carbon nanotubes from Co nanoparticles and C2H2 by thermal chemical vapor deposition

Carbon nanotubes (CNTs) were grown from Co nanoparticles by thermal chemical vapor deposition using C2H2, H2, and Ar gases. The diameters of CNTs were limited by the sizes of the catalytic Co nanoparticles. From 5 nm Co nanoparticles, very long and straight CNTs with diameters below 5 nm were grown. C2H2 was so effective as the carbon feedstock that the required amount of C2H2 was only 0.1% of the total amount of gases to grow CNTs from 5 nm Co nanoparticles. For 8 nm Co nanoparticles, a long enough pretreatment time was essential in growing dense CNTs.