Electrodeposition mechanism of palladium nanotube and nanowire arrays.

Palladium nanotube and nanowire arrays were fabricated by electrodeposition into anodic alumina oxide (AAO) templates. By using alumina templates with different pore sizes and hole mouth morphologies, nanotubes with various diameters and lengths were obtained. The mechanism of nano-structure formation was studied by analyzing the current-time curves. It was found that the time needed for the transformation of the nanostructure from a tube to a wire depends on the size and structure of the template. However, the overall behaviour of the current-time transient is similar and can be divided into four main stages, which provides a powerful in-situ method to control nanotube-nanowire transition during growth. The palladium nanotube arrays have a polycrystalline structure, but a preferred orientation along the (110) direction was observed for the arrays of nanowires. Moreover, the degree of texture increases with decreasing alumina pore size.