Highly ordered anodic alumina nanofibers fabricated via two distinct anodizing processes

Fabrication of high-density, highly ordered anodic alumina nanofibers was demonstrated via two distinct anodizing processes: porous and fibrous oxide formations. Highly ordered aluminum dimple arrays were fabricated via sulfuric/oxalic acid anodizing and selective porous alumina dissolution. Subsequent pyrophosphoric acid anodizing using the nanostructured aluminum surface caused anodic alumina nanofibers to grow preferentially at the six apexes of the ordered hexagonal aluminum dimples under the appropriate electrochemical conditions. Well-defined, high-density, highly ordered anodic alumina nanofibers with 37-75 nm periodic spacing and at densities of 1.4-5.6 × 10¹⁴ m^-2 were successfully fabricated on the aluminum surface via two distinct anodizing processes.