Controlling optical properties of aluminum oxide using electrochemical deposition

We demonstrate here a simple method to tune the optical properties of thin films of nickel nanowires grown inside an anodic alumina oxide (AAO) template using different anodizing conditions. The optical properties of the metal plate can be effectively tuned by adjusting the thickness of porous alumina oxide. In our case, the thickness of the porous alumina oxide depends strongly on the current density because the duration of anodization maintained constant. The transmission electron microscopic image of the cross section reveals the growth of nickel nanowires which are embedded in porous alumina oxide. Due to the interference between incident light and reflected light, the anodic alumina oxide plate exhibits a variety of color. This demonstration of optical behavior tuning makes it possible to scale up the preparation of metal/oxide nanostructures exhibiting color tuning in the visible region.