The effect of the current pulse amplitude on the nanopore structures of 3D-AAO films

The microstructure of porous anodic aluminum oxide (AAO) has a crucial influence on its properties. In this paper, three-dimensional AAO (3D-AAO) film with mallet-shaped nanopores structure and 185–187 nm pore diameters was prepared by periodic pulse anodizing of high-purity aluminum foil in phosphoric acid using asymmetric sawtooth current waves. Highly ordered 3D-AAO membranes with periodically modulated nanostructure were achieved, and the nanopores were changed from mallet shape to Y-branched channels with a length of 249–742 nm by adjusting the amplitude of the asymmetric sawtooth current wave. The effect of current amplitude on the nanostructure of 3D-AAOs was analyzed by combining the scanning electron micrograph (SEM) of the samples and the V-T images during the anodization process. The results show that the anodization time of the high-potential anodization stage and the low-potential anodization stage in each cycle can be adjusted by changing the amplitude of the asymmetric sawtooth current wave, to realize the regulation of the 3D-AAO nanostructure. These 3D-AAO film with structural modulation may be used as templates for the fabrication of novel nanowires or nanotubes with excellent electromagnetic properties. [Display omitted] •Three-dimensional AAO films were prepared using asymmetric sawtooth current waves.•The AAO nanopores were changed from mallet shape to Y-branched pores.•The effect of current amplitude on the nanostructure of 3D-AAOs was analyzed.•The regulation of the 3D-AAO nanostructure was realized by changing the amplitude of the current wave.•These films may be used as templates for the fabrication of novel nanomaterials.