Synthesis, Characterization And Properties Of ZnO Nanostructure

In the common semiconductor, ZnO is one of wide-band-gap semiconductor, andhas many excellent performance. At room temperature having a large exciton bindingenergy, So it become one of the alternative materials of ultraviolet laser. Itsoutstanding optical and electrical properties made it has great application prospect inphotocatalyst, solar cells, gas sensors, nanogenerators. Nanomaterials because of thefactor of size, it has some special effects, Such as quantum size effect, small sizeeffect, surface effect, quantum tunneling effect, the Coulomb blocking effect, anddielectric confinement effect. Therefore, controllable synthesis of ZnO nanomaterialswith different morphologies, and different size is significantly important. Thispapers were synthesized different morphologies of ZnO nanostructures byhydrothermal method and chemical vapor deposition. The main results are as follows:(1)Hierarchical mesoporous zinc oxide microspheres synthesized byhydrothermal method.Hierarchical porous ZnO microspheres have been successfully synthesized bycalcining the microspheric zinc hydroxide carbonate (ZHC) precursor. The ZHC wasformed by zinc nitrate hexahydrate, urea and tartaric acid heated. The products werecharacterized by XRD, SEM, TEM, UV-vis, FTIR, et al. SEM and TEM reveals thatthe as-prepared ZnO microspheres with diameter of2~4μm were assembled bynumerous porous nanosheets which had the uniform thickness about10nm. BETsuggested the ZnO microspheres were mesoporous material, the diameter ofmesoporous were at the range of20~50nm, the specific surface area was about29.8m2/g. By varying the experimental conditions, the influence of the reaction time, thesurface active agent and the reaction temperature on the morphology of the productwere studied. Experimental results show that the surfactant plays a decisive role in theformation of the morphology of the product.(2)Photocatalytic properties of hierarchical mesoporous zinc oxide microspheresThe mesoporous zinc oxide microspheres as a photocatalyst to photode-gradationreaction of methylene blue (MB) under ultraviolet irradiation, the photocatalyticactivity of the ZnO microspheres was evaluated by this experiment. Thephotocatalytic results revealed that the methylene blue solution with an initialconcentration of1.0×10–5mol/L was totally photodegraded by the porous ZnO microspheres after100min irradiation. The results show that the hierarchical porousZnO microspheres exhibit high photocatalytic activeity,and enhanced photocatalyticactivity than commercial TiO2and ZnO.(3)ZnO nanostructures synthesized by chemical vapor deposition methodUsing ZnO powder and carbon powder as raw materials and industrial nitrogen asthe carrier gas, the nanobelts, nanowires, nano-needle of ZnO and chestnut-likeZn-ZnO micro spheres have been successfully synthesized by chemical vapordeposition method under different experimental conditions, and the morphology,crystal structure and luminescence properties of zinc oxide nanostructures werestudied.