Hierarchical Structures: Novel Three‐Dimensional Nanoporous Alumina as a Template for Hierarchical TiO₂ Nanotube Arrays (Small 7/2013)

Hierarchical titania nanotube arrays are replicated from an anodic aluminium oxide membrane with three-dimensionally distributed nanopore structures by D. Wang, L. Liu, and co-workers using atomic layer deposition. On page 1025, anodization in phosphoric acid is accomplished under very harsh conditions using rough, chemically etched, microstructured aluminium foils. The microstructured aluminium provides a unique platform to explore the 3D evolution of oxide nanopores during anodization. More importantly, the resulting 3D nanoporous alumina can act as a general template to fabricate a wide range of hierarchical micro-/nanostructures that cannot be easily realized by conventional physical and chemical means.