Modulation of ionic current rectification direction for biomimetic aluminum oxide membrane by surface modification

A biomimetic aluminum oxide membrane having asymmetric channels with a minimum diameter of 20 nm, maximum 80 and length 5 µm was prepared using square pulse anodization. The effectively permitted transfer anions only showed an ionic current rectification characteristic ratio 2.4. After the sulfonic acid group introduced by surface modification, cations 2.7. This modulation direction consistent theoretical prediction through numerical analysis 2D models. These findings present convenient method to control ion transport for exchange membrane.