Ease of control and switching between ordered free-standing arrays of ZnO nanotubes and nanorods on conductive transparent substrates

Free-standing arrays of ZnO nanotubes and nanorods have selectively been synthesized on indium tin oxide substrates using a template-based electrodeposition method for the first time. The effect of deposition voltage on the growth pattern of Zn in the alumina template has been investigated, providing a tailored ability to reliably produce either nanotubes or nanorods. An annular tungsten base electrode, derived from the anodization of the alumina template, has been found to be crucial to the growth of nanotubes. This method may be adapted for the fabrication of free-standing arrays of other metal and metal oxide nanotubes and nanorods on conducting substrates.

Research highlights
► An annular tungsten electrode is formed during the anodization of the aluminum/tungsten/titanium layer.
► The annular tungsten electrode is the precondition for the formation of ZnO nanotubes.
► The growth patterns of the nanostructures depend on the electrodeposition voltage.
► High electrodeposition voltage results in the formation of Zn nanotubes.
► Low electrodeposition voltage results in the formation of Zn nanorods.