Preparation and photocatalytic activity of porous ZnO and Cr3+ doped ZnO microparticles

In this study, the porous flowerlike ZnO and Cr3+ doped ZnO (Cr3+ = 1 mol%, 2 mol% and 3 mol%) microparticles were successfully synthesized via a simple microwave irradiation process, their structural and photocatalytic properties were systematically investigated. The morphology, physicochemical properties, element state and crystal phase of prepared catalysts were characterized by SEM, XRD, XPS, N-2 adsorption-desorption and AAS, respectively. Besides, the photocatalytic decomposition of Methylene Orange (MO) under solar irradiation also was employed to measure the photocatalytic properties of the pure ZnO and Cr3+ doped ZnO catalysts. The effects of degradation time, Cr3+ doped contents, amount of catalyst, initial dye concentration and pH on photocatalytic activities were analyzed. The results proved that the approach assisted by microwave irradiation was efficient for preparation of microparticles with good morphology, the photocatalytic properties of the obtained ZnO have been greatly improved through doping with Cr3+. And the photocatalytic degradation ratio can reach to 99%, when the doping content of Cr3+ is 2 mol%, pH = 5, after reacting for 150 min. At last, the mechanism of photocatalytic degradation of MO was studied by trapping experiments.