Anodic aluminum oxide (AAO) templates are widely used for the development of various functional nanomaterials due to their highly ordered and tunable porous structures. Here, we report a new hierarchical AAO (hAAO) template with the hexagonally ordered unit cells and the radially distributed nanochannels. It is formed by integrating the self-assembled polystyrene microsphere template into the AAO fabrication process and rationalized in terms of mechanical stress and electric-field-induced oxide dissolution. The back side of the hAAO template resembles a moth-eye-like nanoarray, which shows good hydrophobicity. A variety of radial nanopillar arrays and moth-eye-like nanoarrays are fabricated by a series of materials and synthesis techniques employing the hAAO template. These unique nanoarrays demonstrate many physicochemical properties that are distinct from those obtained from the conventional AAO template.
Keywords: hierarchical anodic aluminum oxide; moth-eye-like nanoarray; radial nanopillar array.