CATALYTIC SYNTHESIS OF SINGLE-LAYER CARBON NANOTUBES WITH A WIDE-RANGE OF DIAMETERS

We have synthesized single-layer carbon nanotubes by co-vaporizing cob alt with carbon in an are fullerene generator and have identified cond itions that lead to high yields. The diameter distribution of the tube s and their morphologies are studied using transmission electron micro scopy. For nanotubes produced using cobalt and carbon, the tube diamet ers range from 1 to 2 nm with distribution peaks at 1.3 and 1.5 nm. Wh en sulfur is added to the carbon and cobalt, production of single-laye r nanotubes is enhanced and the tubes have a wider range of diameters (from 1 to 6 nm). The diameter distribution for these nanotubes shows prominent peaks al 1.3 and 1.5 nm and additional maxima at 2.7 and 3.6 nm. Cobalt-containing crystallites, some encapsulated in graphitic po lyhedra, are produced with the nanotubes and are found in the soot awa y from the cathode.