Fabrication of ultra‐thin alumina membranes utilizing waste aluminum cans

We report on utilizing waste aluminum cans for anodic aluminum oxide (AAO) membranes fabrication. Aluminum (Al) presents in the cans is about 97 % tested via inductively coupled plasma‐mass spectrometry. Synthesis process of the AAO membranes includes heat‐treatment and surface polishing of the waste Al sheets, first anodization, aluminum oxide layer removing, second anodization, aluminum substrate separating and pore‐widening. Thickness and morphology of the prepared AAO membranes are observed through a field emission scanning electron microscopy. By controlling the second anodization time, the AAO membranes possess ultra‐thin thickness in the range of ~60‐650 nm. The average pore densities ~1.2 × 1010 and ~ 3.0 × 1010 hole/cm2 of the AAO membranes are obtained at constant anodization voltage of 40 and 25 V, respectively. Hole diameter of the AAO membranes can be varied from 30 to 95 nm via managing the pore‐widening time. The ultra‐thin AAO membranes with order nano‐hole arrays can be used as hard‐templates which are promising for unique nanostructures synthesis at low cost and environment friendly.