Relationship Between Geometric Structures of Catalyst Particles and Growth of Carbon Nanocoils

The relationship between the geometric structures of catalyst particles and the growth of carbon nanocoils (CNCs) is investigated. It is found that the CNCs usually consist of over two, but less than five tubules. The catalyst particles at the tips of CNCs are all polyhedron structures, in most cases, hexahedron. It is considered that a catalyst particle has two kinds of crystal facets, the catalytically active facet and the carbon precipitation facet. The active facet mainly plays the roles of decomposition of hydrocarbon and diffusion of the formed carbon atoms, while carbon tubules are grown from the precipitation facets and twisted to form a carbon coil. Catalysts with different numbers of active facets and geometric structures form different types of CNCs. Catalyst particles for the growth of carbon nanocoils contain catalytically active facets and carbon precipitation facets. The bending of carbon tubules results from the rate of surface diffusion being larger than that of bulk diffusion. Catalysts with different numbers of active facets and symmetric structures lead to the growth of carbon nanocoils consisting of different numbers of nanotubules.