Preparation of Highly Ordered Anodic Aluminum Oxide Membranes with Wide-Range Tunable Pore Intervals in Mixed Electrolytes

Abstract

Highly ordered anodic aluminum oxide (AAO) membranes with pore interval from 100[Formula: see text]nm to 520[Formula: see text]nm were fabricated successfully in the mixed electrolytes, which are composed of 0.3[Formula: see text]M oxalic acid and 1[Formula: see text]wt.% phosphoric acid/0.01[Formula: see text]M aluminum oxalate. The study results show that oxalic acid volume percentage has an approximate linear relationship with the optimal anodic oxidation voltage. The optimal anodic oxidation voltage is basically equal to the critical oxidation voltage. The theoretical analysis suggests that the anodic oxidation current is closely related to the ionization constants of acid radical ion in the electrolyte. Since the secondary ionization constant of oxalic radical ion is greater than that of phosphoric acid radical ion, the optimal anodic oxidation voltage increases and the steady anodic oxidation current decreases with the decrease of oxalic acid volume percent.