Self-Ordered Anodic Aluminum Oxide Formed by

S elf-ordered nanoporous anodic alumi-num oxide (AAO) is a versatile platformfor applications in the fields of sensing, storage, separation, and the synthesis of one-dimensional nanostructures.1–9 In contrast to mesoporous materials formed by the self-assembly of surfactants and block copoly-mers, AAOs consist of arrays of nanopores with high aspect ratios that may extend sev-eral cm2.10–12 Self-ordered AAOs are ob-tained by mild anodization (MA) in three ma-jor self-ordering regimes with H2SO4, H2C2O4, and H3PO4 solutions as electrolytes under ap-propriate electrochemical conditions.13–18 The MA process, however, requires an anod-ization time of typicallymore than 2 days, and self-ordered pore growth only occurs in nar