Zinc oxide (ZnO) nanostructures were successfully synthesized by thermal oxidation of Zn from different sources in the air atmosphere. We aimed to explore the influence of oxidation temperatures and the type of the Zn sources (powder and sheet) on the morphology and physical-chemical properties of the synthesized ZnO nanostructures. X-ray diffraction pattern and elemental analysis results proved that the applied one-step vapor phase transport synthesis method resulted in the synthesis of high purity ZnO nanostructures. Morphological observations using field emission electron microscopy demonstrated two kinds of morphologies, mostly including tetrapods and a trace amount of multi-pod shaped ZnO nanostructures, synthesized from powder and sheet Zn sources, respectively. Attained ZnO nanostructures were investigated for photocatalytic degradation of the methylene blue dye in aqueous solution under UV-light irradiation. Results showed that the multi-pod shaped (∼93%) sample had slightly better photodegradation efficiency than the tetrapod shaped (∼91%) ZnO nanostructures at 150 min of irradiation time. By adding 20 μl of H2O2 as an electron scavenger agent, the photodegradation process was accelerated and the reaction constant rate showed 218% and 173% improvement for multi-pod and tetrapod shaped nanostructured ZnO particles, respectively. Almost the same photocatalytic efficiency results were attained after 30 min of irradiation with the addition of H2O2 for multi-pod (∼92%) and tetrapod (∼90%) shaped ZnO nanostructures. Photocatalytic reusability of multi-pod shaped ZnO nanostructures was evaluated in the presence of H2O2 and efficiency was only 4% lower than in the first cycle. Finally, the presented results showed the synergetic effect of H2O2 as an electron scavenger agent on the photocatalytic activity of pod shaped ZnO nanostructures due to suppressing the recombination process of electron-hole pairs.
