Large-scale synthesis of few-walled carbon nanotubes by DC arc discharge in low-pressure flowing air

At low-pressure flowing air condition, few-walled carbon nanotubes (FWCNTs) have effectively been synthesized by arc discharge process with iron as a catalyst and sulfur as a promoter. TEM observations show that the as-synthesized FWCNTs with the diameter ranging from 1.6 to 6.0 nm consist of single-walled carbon nanotubes, double-walled carbon nanotubes and triple-walled carbon nanotubes. Our findings reveal that the yield of FWCNTs is found to be dependent on the air pressure, and the air pressure between 6 and 12 kPa is the most effective condition for yielding high quality FWCNTs. This approach presents an effective, low-cost synthesis of FWCNTs using low-pressure flowing air as buffer gas.