A new method detaching porous anodic alumina films from aluminum substrates

Recently, a particular focus on the research of porous anodic alumina (PAA) films is taken because of the application for growth of nanostructure materials. However, during detaching the PAA films from aluminum substrate and opening the holes of PAA films, it is quite difficult to keep intact through-hole structure of PAA films using traditional chemical etching method. Furthermore, the traditional method is time-consuming and has contamination because of the use of heavy metal ion solution. Usually, the preparation time is over 20 h. In our work, a new electric- chemical method was proposed for detaching PAA films and opening the holes of PAA films in an environmental friendly solution of HClO₄-CH₃OH in one step. The preparation process can be finished within 5-15 s. Compared with traditional etching method in which there are two-step processes, the electric-chemical method is simple, rapid and contamination-free. A large size PAA films with intact through-hole structure can be obtained.