Synthesis of regular coiled carbon nanotubes by Ni-catalyzed pyrolysis of acetylene and a growth mechanism analysis

Many efforts have been made to synthesize carbon nanotubes by means of arc discharge, laser ablation, ion beam irradiation, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), etc. Among the many experimentally observed morphologies gathered so far, straight and anomalous curl are the two most dominant shapes. For instance, Hernadi et al. reported on the formation of nanotubular coils by Fe-catalyzed pyrolysis of acetylene. Up until now, however, no regular coiled carbon nanotubes have been reported. Theoretically, coiled carbon nanotubes would provide excellent properties. In this letter, the synthesis of regular coiled carbon nanotubes by Ni-catalyzed pyrolysis of acetylene along with its growth mechanism is reported.