Preparation and photocatalytic properties of zinc oxide nanoparticles by microwave-assisted ball milling

Hexagonal wurtzite ZnO nanoparticles with the average size of about 15 nm were successfully prepared by microwave-assisted ball milling. The as-prepared ZnO nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–visible spectrophotometer, fluorescence measurements, and electroconductivity detections. The results showed that single-phase hexagonal wurtzite ZnO nanoparticles were obtained after 20 h by microwave-assisted ball milling. The UV spectrophotometer analysis confirms that photocatalytic activity of as-synthesized ZnO nanoparticles under ultraviolet light is demonstrated via methyl orange degradations of 95%. In addition, the measurement results of the relative content of OH radicals in the aqueous solution and the relative conductivity of the solutions verify that the coupling of microwave and ball milling significantly enhanced the chemical reaction.