Morphogenesis of ZnO nanostructures: Role of acetate (COOH^-) and nitrate (NO₃^-) ligand donors from zinc salt precursors in synthesis and morphology dependent photocatalytic properties

We have studied the anion ratio effect of acetate and nitrate ions on the formation of different morphologies of ZnO crystals in the presence of NaOH and HMTA. We have varied the concentration of zinc salt precursors as well as adopted three different methods of synthesis (chemical, ultrasonic and hydrothermal) to study their effects on the size/shape of the formed ZnO nanostructures. We found that these anions which spontaneously get introduced along with zinc salt can modify the structure depending on their ratio. The photocatalytic properties of the as obtained ZnO nanostructures (nanoflower, nanospindle and nanorod) were tested towards anionic dye methyl orange. The results show that rod like ZnO nanostructures are catalytically more reactive than nanoflowers and nanospindles. Based on these results we propose that selection of appropriate zinc salt is important to rationally design experiments for a particular morphology. Furthermore, it is also suggested that the role of other precursor salts in synergy will lead to the formation of various nanostructures and this can be extended to other metal oxides of interest for modification.