Formation mechanism of individual alumina nanotubes wrapping metal (Cu and Fe) nanowires

Using electrochemical deposition onto porous anodic alumina membrane and subsequent ultrasonic treatment, we have obtained individual alumina nanotubes wrapping metal (Cu and Fe) nanowires with nanocrystalline structure, which are a kind of conventional nanocable prototype. Scanning electron microscope and transmission electron microscope observations and X-ray diffraction, energy dispersive X-ray fluorescence, and selected area electron diffraction analyses clearly show the formation of a composite nanotube structure. Its formation mechanism is discussed on the basis of microstructural characterization. Our experiments provide a useful way for fabricating low-cost and large-scale metal nanocables, which will be of important applications in nanodevices.