Growth of multi-walled carbon nanotubes by catalytic decomposition of acetylene on Ni-supported carbon fibers prepared by the heat-treatment of cellulose fibers

Cellular-type carbon fibers, prepared by heat-treatment of cellulose fibers that ranged from 500 to 2300 A degrees C, were used as catalytic support for the growth of carbon nano-filaments. A comparison of the Raman spectra of products prepared at different heat-treatment temperatures showed significant variation in the carbon structure of the surfaces of the as-prepared carbon fibers. TEM observation clearly revealed that the products heat-treated below 1000 A degrees C had an amorphous phase, and at 1500 A degrees C they were similar to glassy carbon-an example of non-graphitizing carbon. Surface graphitization of the carbon fibers derived by pre-treatment at 1500 A degrees C was accomplished at above 2000 A degrees C. Multi-walled carbon nanotubes (MWCNTs), approximately 15 nm and 8 mu m in diameter and length, were synthesized on the surface of the prepared carbon fibers via a tip growth mechanism. TEM images and Raman spectra confirmed that the higher synthesis temperature could lead to the formation of MWCNTs with better crystalline carbon shells.