Morphology and microstructure of spring-like carbon micro-coils/nano-coils prepared by catalytic pyrolysis of acetylene using Fe-containing alloy catalysts Original Research Article

Three-dimensional (3D) spring-like carbon nano-coils were obtained in high purity (nearly 100%) and high yield (20%) by the catalytic pyrolysis of acetylene at 750–790 °C using an Fe-based catalyst; 54Fe–38Cr–4Mn–4Mo or 71Fe–18Cr–8Ni–3Mo (SUS513). The morphologies and microstructure were examined in detail, and the growth mechanism is also discussed. The diameter of carbon fiber, from which the carbon nano-coils was formed, was 50–200 nm, the coil diameter 100–1000 nm, and the coil pitch 10–500 nm. The nano-coils were generally grown by a mono-directional growth mode, and laces with various morphologies were very commonly observed on the surface. It was observed that the spring-like carbon nano-coils are actually composed of two fused nano-coils.