Hydrothermal oxidation synthesis of rod-like ZnO and the influence of oxygen vacancy on photocatalysis

Rod-like ZnO nanoparticles (NPs) were synthesized from zinc powder by a simple hydrothermal oxidation method. The presence of acetylacetone could promote the oxidation reaction of Zn and the formation of hexagonal nanorods. Then, the as-prepared samples were annealed in N-2, O-2, and air atmosphere at 550 degrees C for 2h to control the number of oxygen vacancies in the samples. The samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-vis spectroscopy. The correlation between the oxygen vacancies and the photocatalytic activity was investigated. The results reveal that the annealing process alters the samples' bandgap and number of the oxygen vacancies, thereby improving the photocatalytic activity. The enhancement of photodegradation efficiency arising from the appropriate content of oxygen vacancies is discussed.