Direct electrodeposition of ZnO nanotube arrays in anodic alumina membranes

Semiconductor ZnO nanotube arrays have been synthesized by direct electrochemical deposition from aqueous solutions into porous anodic alumina membranes. Scanning electron microscopy and transmission electron microscopy indicate that large-area and highly ordered nanotube arrays have been obtained. X-ray diffraction and selected-area electron diffraction analyses show that the as-synthesized nanotubes are polycrystalline. Photoluminescence spectra of the ZnO nanotube arrays show that a violet peak and a blue peak are centered at 414 and 464 nm, respectively. The ordered polycrystalline ZnO nanotube arrays may find potential applications in optoelectronic and sensor devices. The growth mechanism and the electrochemical deposition process are discussed.