Controlling nanotube chirality and crystallinity by doping

The process of producing highly crystalline thick multi-walled carbon nanotubes (MWNTs) with three-dimensional (3D) order using chemical vapor deposition (CVD) was analyzed. The process involved thermolysis of toluene/1,4-diazine solutions containing 2 wt% ferrocene under an Ar atmosphere at 760°C. It was found that these tubes contain 3% nitrogen and exhibit an extremely high crystallinity similar to that of 3D graphite. It was also found that MWNTs with high 3D order can be produced at low temperature via CVD processes, where N atoms control the nanotube chirality. X-ray photoelectron spectroscopy (XPS) shows that nitrogen bonds to carbon shows a nitrile- and pyridine-like structure and N-doped carbon material shows enhanced oxidation resistance.