Gold nanotubes by template-directed synthesis.

Gold nanotubes were prepared by radiofrequency (RF)-sputtering through a template-directed synthesis in porous alumina substrates. The resulting composite material was subsequently treated in acidic or alkaline aqueous solutions in order to selectively remove the membrane, thus resulting in the obtainment of self-supporting Au nanotubules. The adopted strategy allows the preparation of both composites and free-standing metal nanostructures with an aspect ratio tunable as a function of the synthesis conditions and the membrane pore size.