Cathodoluminescence characterization of Zno/Zns nanostructures anodized under hydrodynamic conditions

ZnO/ZnS nanostructures were successfully synthesized by a simple electrochemical anodization of zinc in a glycerol based electrolyte containing sulfide-ammonium fluoride. The influence of different hydrodynamic conditions and anodization potentials during anodization on the morphological and electronic properties of the obtained ZnO/ZnS nanostructures was studied. The anodized samples were characterized using confocal Raman microscopy, X-Ray Diffraction (XRD), Field Emission Scanning Electronic Microscopy (FE-SEM), cathodoluminescence (CL), and photoelectrochemical water splitting tests under standard AM 1.5 conditions. The results showed that hydrodynamic conditions and higher potentials promoted the formation of ZnO/ZnS nanotubes with both higher sulphur content and crystalline defect density, which reduces the near band edge transition value of the materials and improves the photoelectrochemical activity for water splitting. Additionally, the higher photocurrent densities for water splitting were obtained for the samples anodized at the highest anodization potential and under hydrodynamic conditions, increasing in a 71% for the nanostructures anodized at 1000 rpm when the anodization potential changes from 20 to 40 V.