Synthesis, Characterization And Photocatalytic Properties Of Nanosized ZnO And TiO₂-ZnO

Compared with the traditional bulk materials, the advantages of nanometer materials are self-evident. Because of the quantum size effect, minor dimension effect, surface effect and interface effect, nanometer materials possess a series of excellent properties, including electronic, magnetic, optics, mechanical, optoelectronic and so on. Especially in the challenge regions of photocatalyzing and photoelectric tranformation, nanometer semiconductor materials display unique superiority. The use of nanometer semiconductors for the photocatalytic degradation of organic pollutants in aqueous waste has gained considerable attention. The photogenerated electrons (e") and hole (h+) migrate to nanocrystal surface, where they act as redox sources, ultimately leading to the destruction of pollutants.Nanometer TiOa, ZnO are widely used as photocatalyst because of its optical and electronic properties, low cost, chemical stability and non-toxicity. In our work, using ZnSO44 ?7H2O as raw material, nanometer ZnO was synthesized by direct precipitation method, homogeneous precipitation method and hydrothermal method respectively, the samples were investigated by XRD, TEM, SEM, TG-DTA, FTIR and ultraviolet visible spectrophotometer respectively. The results show that nanometer ZnO can be obtained by the three methods, the direct precipitation method can be controlled easily. The size of the sample obtained by direct precipitation method is the smallest and the UV-Vis absorption is the strongest. It is also found that using sunlight as the light source the decolorization rate of the dye solution and the elimination rate of CODcr can be close to 100%. Basing on the photocatalyzing effect, nanometer ZnO can be applied in many fields, such as environmental protection, wastewater disposition, decomposition of organic substance and decomposition of inoperative pesticide,In view of the disadvantages of the pure nanometer semiconductor photocatalyst, using TiCl4, ZnSO4 ?7 H2O as raw materials, the nanometer particles of TiO2/ZnO were prepared by microwave irradiation method (MWI). It was characterized by XRD, TEM. EDS. FTIR and ultraviolet visible spectrophotometer respectively. It was found that the coupled material is more acid-resistant and basic-resistant than pure ZnO, the utilizationrate of visible ray can be improved greatly. The dynamics research shows that the photocatalytic degradation reaction is a first-order reaction.