Influence of pH on hydrothermally derived ZnO nanostructures

Zinc oxide (ZnO) nanostructures with numerous morphology was prepared by using hydrothermal method. The effect of pH on structural, optical and photocatalytic activity of ZnO was investigated systematically. The prepared ZnO samples were characterized by various characterization techniques. The X-ray diffraction study revealed that the crystalline hexagonal phase of ZnO nanostructures was observed. Scanning electron microscopic observations revealed that the variation of pH significantly alters the morphology of the grown ZnO nanostructures. The UV-vis spectrum shows an optical bandgap was not significantly influenced by pH of reactant solution. Photoluminescence studies at room temperature for different pH values revealed a weak band edge emission altogether with strong defect-related visible emission peaks. Photocatalytic activity of methylene blue (MB) under visible light illumination was studied. Maximum degradation of 99% was observed in 100 min for ZnO nanostructure prepared at pH 11.