1. Aluminum anodization

The history of electrochemical oxidation of aluminum dates back to the beginning of the last century. Anodic treatment of aluminum were intensively investigated to obtain protective and decorative films on its surface [1]. More recently, applications of porous alumina with a huge surface area and a relatively narrow pore size distribution have been exploited [2]. For example, several attempts to fabricate inorganic membranes have been reported [3, 4, 5]. Nowadays, porous alumina is one of the most prominent template materials for synthesis of nanowires or nanotubes with monodisperse controllable diameter and high aspect ratios [6, 7, 8, 9, 10, 11, 12, 13, 14]. Moreover, it can be employed as a 2-D photonic crystal.