Preparation, characterization and photocatalytic activity of Co-doped ZnO powders

ZnO powders with different Co2+ doping concentrations (0, 0.5, 1, 3 and 5 mol%) were prepared by the hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectrometer, and photochemical reaction instrument. The results show that the ZnO powders are hexagonal wurtzite structures and their crystallization decrease with the increase of Co2+ doping concentration. The products are spherical which have diameter of about 200 nm, and their absorption edge shift to longer wavelength with the increase of the Co2+ concentration. The photocatalytic activities of the powders are evaluated using a basic organic dye, methyl orange (MO). Compared with undoped ZnO, it is found that the photocatalytic properties of the Co-doped ZnO have been improved greatly. When the doping concentration is 3 mol%, the degradation ratio of MO can reach 78% after reacting for 240 min.