Continuous hot wire chemical vapor deposition of high-density carbon multiwall nanotubes

Hot wire chemical vapor deposition (HWCVD) has been adapted to be a continuous growth process for high-density carbon multiwall nanotubes (MWNTs). MWNT growth is optimized in 1:5 CH4:Ar at 150 Torr with reactor temperatures of 400 and 550 degreesC for static and flowing gases, respectively. Ferrocene is employed to provide a gas-phase catalyst. Highly graphitic nanotubes can be continuously deposited with iron content as low as 15 wt % and carbon impurities below thermal gravimetric analysis detection limits. The MWNTs are simply purified to similar to99.5 wt % with minimal structural damage and with a 75 wt % yield.