Highly efficient synthesis of carbon nanocoils by catalyst particles prepared by a sol–gel method

Carbon nanocoils (CNCs) have been synthesized by thermal chemical vapor deposition (CVD) using Fe–Sn–O catalyst prepared by a sol–gel process. Three kinds of catalyst precursors, Fe2(SO4)3/SnCl2, FeCl3/SnCl2 and Fe(NO3)3/SnCl2, were selected. It is found that the catalyst prepared by the combination of Fe2(SO4)3/SnCl2 exhibits the highest catalytic activity, which would be resulted from a small amount of sulfur existing in the catalyst. The highest yield of carbon deposits (mass ratio of deposits to catalysts) is 2510 wt.%. The synthesized CNCs are composed of hollow tubules with average coil diameter and line diameter of approximately 500 and 300 nm, respectively. It is also found that the growth of CNCs is greatly affected by reaction conditions, such as reaction time and temperature. Raman spectral analysis indicates that the higher flow rate of acetylene, the more graphite structures in CNCs.