Effect of catalyst pretreatment on the growth of carbon nanotubes

Abstract

Carbon nanotubes is synthesized by thermal chemical vapor deposition using acetylene as hydrocarbon gas on Ni-coated silicon substrate. The ‘worm-like’ carbon fibers and ‘spaghetti-like’ carbon nanotubes is grown at 700 °C with the Ni catalyst treated by thermal annealing and H 2 plasma, respectively. It is found that the H 2 plasma treatment is a crucial step to maintain the activity of catalyst prior to the reaction of acetylene gas for the nanotube growth. After clarifying this phenomenon, the carbon nanofibers can successfully be grown at low temperature (500 °C). The field emission test shows both the carbon nanotubes and carbon nanofibers have low turn-on voltage and high emission current, which is sufficient for practical application in the carbon nanotube-/nanofiber-based field emission displays.