Effect of solution pH and ZnCl2 on zinc oxide nanostructures grown on Zn foil

Abstract

Zinc oxide (ZnO) nanostructures were formed by wet oxidation of zinc (Zn) foil in water at 90C for 4 h. The effect of pH and ZnCl2 concentration on the morphology and structure of the resulting ZnO nanostructures on the surface of Zn foil were investigated. Clusters of ZnO nanosheets were visibly grown on top of hexagonal flat-topped nanorods in the presence of 0.05 M ZnCl2. Addition of higher ZnCl2 concentration resulted to layered plate-like structures of simonkolleite compound (Zn5(OH)8Cl2H2O). The formation of this compound is favored at high concentrations of Zn2+and Cl- ions. In addition, flower-like structures of hexagonal nanorods, coarse nanorods and nanotubes were obtained at increasing pH values from 6.3 to 10. The increased concentration of OH- ions possibly hindered further deposition of hydrolyzed Zn(II) ions and the subsequent dissolution and redeposition of the existing ZnO nanostructures directed the formation of coarse nanorods and nanotubes.