Fabrication of tunable hierarchical ZnO nanostructures via an anodization process

[Display omitted] •Hierarchical ZnO nanoflowers were prepared for the 1st time via anodization process.•Hexagonal wurtzite phase has been confirmed from the XRD analysis.•Fluoride ions play a crucial for the formation of hierarchical ZnO nanoflowers.•Electrolytes and anodization voltage also play a role on growth of ZnO nanostructures.•Raman spectrum analysis also confirmed the hexagonal wurtzite structure. The size and morphology of nanomaterials replicate optical, electrical, and mechanical properties and their applications. In this paper, for the first time, ZnO hierarchical nanostructures were grown on Zn foil through electrochemical anodization in the presence of fluoride ions at room temperature in water/glycerol electrolyte. Fluoride ions are vital for development of chelation reactions and the formation of ZnO hierarchical nanostructures. XRD analysis confirmed the ZnO crystal phase to be wurtzite, and the Raman analysis confirmed the crystal phase to be wurtzite hexagonal. The surface morphology of ZnO reveals that the nanostructures grown on Zn foil are hierarchical nanoflowers with an even distribution. The identified binding energies from the XPS spectrum confirmed the Zn2+ state. Such unique hierarchical architectured ZnO can be used for designing high-performance optoelectronic devices such as LED lights, photodiodes, nanosensors, and solar cells.