Effect of oxygen and hydrogen addition on the low-temperature synthesis of carbon nanofibers using a low-temperature CO/Ar DC plasma

The low-temperature synthesis of carbon nanofibers was demonstrated. When a small amount of O-2 was added to the CO/Ar plasma, the diameter of the CNFs decreased and the deposition of amorphous carbon and fiber bundling were suppressed. On the other hand, when H-2 was added, the diameter increased, and at higher H-2 flow rates, only smooth carbon film was deposited. At the optimum oxygen concentration of CO/O-2=1/0.003, vertically aligned free-standing CNFs can be synthesized at low temperature as low as 90 degrees C. Our spectroscopic study reveals that there is a steady correlation between C-2 radical formation and CNFs growth. (C) 2008 Elsevier B.V. All rights reserved.