A New Method for Highly Efficient Fabrication of Through-Hole Porous Anodic Alumina Membranes

Abstract

Two-step anodization in 0.3 M oxalic acid electrolyte is used to grow highly ordered porous anodic alumina on both sides of Al sheet. The obtained sample is annealed and subsequently the annealed sample is re-anodized, producing two-layer PAAs on the Al. Since the re-anodized PAA has much higher etching rate than the annealed, it can be taken as a sacrificial layer to be selectively dissolved. As a result, through-hole PAAs are detached and highly ordered concaves maintain on the Al surfaces. So the Al sheet can be repeatedly used for highly efficient fabrication of through-hole PAAs. This method is also suitable for producing through-hole PAAs in other electrolytes, such as sulfuric acid and phosphoric acid.