Zinc oxide nanostructured films produced via anodization: a rational design approach

Abstract

Nanostructured zinc oxide films were produced through anodization of zinc foil by using different electrolytes at different voltages, temperatures and over different time periods. The ZnO films were characterised by studying their surface morphology using FESEM, crystal structure using XRD, wetting behaviour through contact angle measurement, and also measuring the profile of the ZnO layer and band gap. Results show that the type of electrolyte and its concentration determine the morphology and size of the nanostructures. Voltage, time and temperature affect the distribution and density of the nanostructures along the surface. The band gaps of the films were in the range of 3.27 to 3.50 eV. Although ZnO is a hydrophilic material, some of the films display hydrophobic and super-hydrophobic behaviour. The data obtained in this study were combined with literature studies and used to devise design guidelines to obtain ZnO films with specific nanostructures and macroscopic properties by controlling the anodization parameters.