Evolution of the Pore Size Distribution in Nanoporous Alumina Membranes with Anodization Voltage in Oxalic Acid

The effect of voltage on nanopores formed via electrochemical anodization of high purity Aluminum was investigated. The electrochemical bath consisted of a 0.3 M oxalic acid electrolyte. A platinum electrode was used as the counter-electrode, and an aluminum sheet as the anode. The anodization process was carried out at a temperature of 7 ° C at various voltages ranging from 30 to 55V. It was observed that during the anodizing process, both the current density and the nanopore size increase as the applied voltage increases. The morphology and the distribution of nanopores were analyzed by SEM (Scanning electron microscope). It was found that mean pore diameter increased from 43 to 100 nm as the voltage is increased from 30 to 55 V. the polydispersity of the pore size was found to be minimum at 40 V.