Synthesis of multi-walled and single-walled nanotubes, aligned-nanotube bundles and nanorods by employing organometallic precursors

Pyrolysis of organometallic precursors such as metallocenes and iron pentacarbonyl as well as of their mixtures with hydrocarbons such as acetylene or benzene has been carried out under a variety of conditions to synthesize nanotubes. While the use of benzene as a hydrocarbon source generally yields multi-walled nanotubes, it has been possible to obtain single-walled nanotubes (∼1 nm diameter) by pyrolyzing a metallocene or a mixture of metallocenes along with acetylene under a high flow rate of Ar. These experiments show that the organometallic precursor produces small nanoparticles of ∼1 nm diameter which then catalyze the formation of the single-walled nanotubes. Copious quantities of aligned-nanotube bundles have been obtained by the pyrolysis of acetylene in the presence of high concentrations of ferrocene. Nanorods have been produced by the pyrolysis of ferrocene under vacuum. Single walled nanotubes can be filled or decorated by metals.