Fabrication of thin-film spherical anodic alumina oxide templates using a superimposed nano-micro structure

Abstract

Compared to the single-scale planar anodic aluminum oxide (AAO) film, the multi-scale hierarchical AAO structures can have a better performance due to the larger surface area. The conventional multi-scale AAO structure on a micro-pattern surface was fabricated using time-consuming lithography and etching process at high cost. In this article, the 3D porous AAO films with nanopores of 35–45 nm in diameter have been achieved on the surface of silica micro beads of 2 μm in diameter. The superimposed nano-micro structure was fabricated using hybrid-pulse anodizing the sputtered Al film on beads with a period of negative potential to dissipate Joule heating at room temperature. The 3D AAO-on-beads structure provides a large-surface-area substrate for enhancing the sputtered TiO2 photocatalysis. The photocatalysis on the superimposed nano-micro structures can exhibit a high performance with the MB concentration of 30% after 15 h photo-degradation.