Preparation of porous anodic alumina with periodically perforated pores.

Anodization of aluminum is an excellent nonlithographic alternative to conventional fabrication approaches for low-cost and large-scale synthesis of a variety of nanostructured materials. In this work, the preparation of anodic alumina oxide (AAO) with unique three-dimensional (3D) porous structures that consist of periodically perforated nanopores is reported. The fabrication method combines electrochemical anodization of aluminum and chemical etching. The key feature of this process is cyclic anodization where an oscillatory current signal was applied to create AAO with periodically shaped pore structures. Spatially specific dissolution of the pore walls was directed by modulated pore structures during chemical etching to generate hexagonally ordered arrays of holes with periodic distribution across the pore length.