Parametric study on growth of carbon nanocoil by catalytic chemical vapor deposition

Carbon nanocoils (CNCs) were synthesized by the catalytic pyrolysis of acetylene over a mixture of Fe and SnO2 particles in a chemical vapor deposition (CVD) apparatus. The effects of reaction temperature, the composition of Fe and SnO2 in the catalyst, and the ratio of acetylene (C2H2) to helium (He) gas were examined. An optimum output was obtained when the Fe/ SnO2 ratio was 2/1, the flow rates of C2H2 and He gases were 150 and 700 sccm, respectively, and the reaction temperature was 700 degrees C. Under these conditions, the CNCs were of 80% purity, with average coil diameters of 750 nm, fiber diameters of 300 nm and pitches of approximately 750 nm. The CNC yield weighed up to 60 times that of the catalyst in 10 min.