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 O2 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 H2 was added, the diameter increased, and at higher H2 flow rates, only smooth carbon film was deposited. At the optimum oxygen concentration of CO/O2 = 1/0.003, vertically aligned free-standing CNFs can be synthesized at low temperature as low as 90 °C. Our spectroscopic study reveals that there is a steady correlation between C2 radical formation and CNFs growth.