Non-Catalytic Low-Temperature Synthesis of Carbon Nanofibers by Plasma-Enhanced Chemical Vapor Deposition in a CO/Ar/O2 DC Discharge System

Abstract

Catalyst-free low-temperature growth of carbon nanofibers was performed by a plasma-enhanced chemical vapor deposition using a CO/Ar/O2 DC discharge system. At the optimum oxygen concentration of O2/CO = 0.002–0.005, vertically aligned carbon nanofibers with a diameter of about 10–50 nm can be synthesized at temperatures as low as 90 °C without any catalyst materials. It is concluded that the addition of a small amount of O2 is the key to the synthesis of carbon nanofibers without a catalyst, because it suppresses the isotropic deposition of amorphous carbon while allowing the anisotropic linear growth of crystallized carbon materials.