Hierarchical ZnO Nanostructures Obtained by Electrodeposition

We present a two-step electrochemical deposition process to produce hierarchical ZnO nanostructures that involves the electrodeposition of ZnO crystals with different morphologies, followed by the electrochemical epitaxial growth of oriented nanorods on the surfaces of the primary ZnO nanostructures. A variety of hierarchical ZnO nanostructures, including 2-fold nanorod arrays on nanosheets, 6-fold nanorods on nanorods, and 6-fold nanoneedles on nanoneedles, were synthesized on a large scale. The hierarchical nanostructures obtained by this technique are pure and uniform in morphology. Furthermore, we demonstrate that the hierarchical ZnO nanostructure of nanorods on nanosheets provides a good candidate for photoanodes in dye-sensitized solar cells.