Patterned growth of coiled carbon nanotubes by a template-assisted technique

A method for controlled synthesis of coiled carbon nanotubes (CNTs) is demonstrated, in which three-dimensional columns of aligned CNTs are used as a template. The coiled CNTs with pitches and coil diameters from 100 to 300 nm are regrown on the straight CNT arrays and the mesoporous structure between the CNT arrays produces an asymmetric growth condition for the coil formation. As observed using transmission electron microscopy, the graphitic layers on the tube wall are stacking-disordered due to the coil geometry. The growth mechanism of the coiled CNTs is also proposed.