Generation and Growth Mechanism of Metal (Fe, Co, Ni) Nanotube Arrays

10.1002/cphc.200500690.absNanotubes composed of layered or nonlayered materials have been synthesized through various methods, among which template‐based electrodeposition technology provides a versatile technique for synthesizing one‐dimensional nanostructured materials. However, the growth mechanism of nanotubes using the template method is seldom clarified. Herein, we present the systematic preparation of metal nanotube arrays and put forward the growth mechanism, termed current‐directed tubular growth (CDTG), for template‐based electrodeposition. There are competitive growth rates for metal atoms entering the crystal lattice, that is, v∥ (growth rate parallel to current direction) and v⊥ (growth rate perpendicular to current direction). Metal nanotubes can be obtained at v∥≫v⊥, while nanowires can be obtained at v∥≈v⊥. The as‐synthesized metal (Fe, Co, Ni) nanotubes are constructed from nonlayered materials, which are of body‐centered cubic iron structure, hexagonal close packed cobalt structure, and face‐centered cubic nickel structure, respectively. The CDTG mechanism is expected to have applications in designing and synthesizing other metal nanotubes and even compound nanotubes via template‐based electrodeposition technology. Growth factors: Metal nanotube arrays (see scanning electron microscopy image) are synthesized by a template‐based electrodeposition method via a growth mechanism termed current‐directed tubular growth. The growth rates are competitive parallel and perpendicular to the current direction, which results in either nanotubes or nanowires. Nanotubes of Fe, Co, and Ni with nonlayered structures are produced at an increased current density.