Control on the morphology and photoelectrocatalytic properties of ZnO nanostructures by simple anodization varying electrolyte composition

Zinc oxide nanostructured electrodes were successfully synthesized by a simple method of anodization in different aqueous bicarbonate electrolytes. The influence of the anodization electrolyte composition (by adding ethanol or glycerol) on the morphology and the photoelectrocatalytic properties of the zinc oxide electrodes was studied, as well as the combined effect of anodizing under controlled hydrodynamic conditions. Field Emission Scanning Electron Microscope (FE-SEM) images of the ZnO electrodes showed that the addition of ethanol or glycerol to the anodization electrolyte resulted in changes in size and morphology of the nanostructures. Thus, ZnO nanowires, nanotubes, nanosponge and nanospheres were obtained. Additionally, multi-factor analysis of the variance (ANOVA) revealed that photocurrent density response during water splitting test experimented significant variations depending on the anodization electrolyte composition. In particular, the best photoelectrochemical performance was achieved for the ZnO nanostructures anodized in low amounts of ethanol or glycerol.