Preparation of self-ordered nanoporous anodic aluminum oxide membranes by combination of hard anodization and mild anodization

摘要

Anodic aluminum oxide (AAO) is one of the most important templates for fabrication of nano-materials. In this paper, we present a fast two-step anodization method to prepare self-ordered AAO films. The first step is hard anodization (HA) in H_2SO_4 and the second step is mild anodization (MA) in H_2C_2_4. HA in H_2SO_4 at a wide range of anodization voltage provided a fast formation of ordered arrays of pits on Al sheet, and in the second step, arrays of pits on Al substrate affected nucleation initially, and the anodization voltage of H_2C_2_4 M.A. determined the degree of AAO later. Then the best anodization voltage of H2C204 M.A. was validated to be around 40 V. The improved combination of HA and M.A. not only shortens the time of the first anodization step compared to conventional two-step anodization which was reported by Masuda and Fukuda (1995), but also keeps a highly ordered AAO within large area. Moreover, the relationship between the size of arrays of pits formed in H_2SO_4 HA and degree of order of AAO formed in H_2C_2_4 M.A. was investigated in detail.