Synthesis of Y-junction Carbon Nanotubes from Graphite Composites by Arc-discharge

Y-junction carbon nanotubes were synthesized by arc discharge method from composite anode made of graphite powder, coal tar and alloy catalysts consisting of Fe, Ni, Co and S element. The synthesis of Y-junction carbon nanotubes was carried out in a mixture gas of 200 Torr Ar and 100 Torr H2. The as-synthesized Y-junction carbon nanotubes were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDX). The results show that the Y-junction carbon nanotubes with short branches are long multi-wall carbon nanotubes with walls more than 20 nm in thickness and high graphitic degree. It can be found that the length of most branches is less than 5 micrometers and the angle between the stem and branches is in the range of 60-150. The EDX analysis reveals that the catalysts located at the Y-junction are alloys consisting of Fe, Ni, Co and S element. A growth process is proposed to explain how the YCNTs are formed.