Controllable morphology evolution of electrodeposited ZnO nano/micro-scale structures in aqueous solution

This study introduces a cost-effective electrodeposition route for preparation of highly oriented and well-defined ZnO nano/micro-scale structures on indium tin oxide (ITO) glass substrates without a traditionally pre-prepared layer of ZnO seeds. It was demonstrated that the addition of KCl, NaCl, and ethylenediamine (EDA) and the hydrolysis of hexamethylenetetramine (HMT) pose the difference in growth rates between ZnO {1 0 over(1, ̄) 0} prismatic planes and (0 0 0 1) end plane and lead to the formation of highly oriented ZnO rods, flower-like ZnO bundles, nanowire arrays or hexagonal plates. The effect of different Cl^- sources on the array manner of ZnO plates and the effect of concentration of EDA on the aspect ratio of ZnO rods were investigated, respectively. Electrodeposition potential plays an important role in the preferential growth orientation of ZnO crystals on the substrates without a traditionally pre-prepared layer of ZnO seeds. Room temperature photoluminescence (PL) properties of different ZnO structures were also investigated. In addition, different procreation manner on the (0 0 0 1) growing end planes for ZnO rods and nanowire arrays were observed. On the basis of observation, several growth mechanisms, such as layer-by-layer procreation manner for ZnO nanowires, are suggested.