Oxidation of etched Zn foil for the formation of ZnO nanostructure

Oxidation of Zn foil at temperatures of 100–400 °C was carried out in air to produce ZnO with various nanostructures. The final morphology of the oxidised Zn foil is largely dependent on the oxidation temperatures. At less than 300 °C, spherical oxide grains are seen. At 400 °C, 50 nm thick, porous nanosheets were formed after 30 min of oxidation. In portions of the samples, nanorods can be seen with diameters <10 nm and lengths reaching 1 μm. The nanosheets were formed in accordance to a vapour–solid mechanism whereas the nanorods were formed by diffusion of Zn through a certain path leading to the rod structure. At 450 °C, the nanorods became much more uniform. Oxidation at 500 °C resulted in ZnO nanorods. The rods are also blunt with smaller rods seen to branch out from the main rod. The luminescence properties of the ZnO were investigated as a function of the morphology of the oxide. Both green and blue emissions are seen for the samples with nanosheets whereas the nanorods ZnO has mostly green emission.

► This paper focuses on the formation of ZnO nanostructures by thermal oxidation of etched Zn foil.
► Depending on the oxidation temperature, ZnO nanosheets, nanorods or branched nanorods can be formed.
► The mechanism of the formation of these nanostructures is presented in here along with the photoluminescence properties of the nanostructures.
► Thermal oxidation is indeed a simple yet effective way for the formation of ZnO nanostructure.