Construction Of Hierarchical Micro/Nano ZnO Structure And Their Photocatalytic Properties

Zinc oxide, one of the metal oxides, is a semiconductor material with a wide band gap about3.3eV atroom temperature, and owns an exciton binding energy of60meV, and has a good thermal stability. Also,it is varied in the methods of preparing ZnO, which makes the different change of its morphology. As aresult, it has a wide application in solar cells, gas sensors, photocatalysis, etc. Here, we make some researchin getting different morphology of ZnO, the main work is as follows:1) Control growth of single crystalline ZnO nanorods arrays and nanoflowers with enhanced photocatalyticactivitySingle crystalline vertical nanorods arrays and nanoflowers of ZnO have been in situ grown on cheapzinc foils, with the help of ethanolamine (EA) and hexamethylenetetramine (HMT) under hydrothermalconditions, respectively. Their morphologies and crystal structures are characterized by X-ray diffraction(XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy(HRTEM). The possible synthetic mechanisms of the as-prepared ZnO nanostructures are discussed in ourstudy. Both types of ZnO display high photocatalytic ability towards the degradation of methylene orangeunder UV irradiation, while the ZnO nanorods show superior activity than the ZnO nanoflowers.2) Gelatin-assisted hydrothermal synthesis of ZnO nanostars and its photocatalytic propertiesBiotemplate-assisted approach is simple and friendly to the environment. With the assistance ofgelatin as a structure-directing agent, star-like ZnO nanostructures have been prepared by assembly ofnumerous well-defined nanorods under hydrothermal conditions. Their morphology and structures werecharacterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electronmicroscopy (HRTEM). The formation mechanism of the ZnO nanostars is also studied, which isaccordance with the morphological changes by varying the experimental conditions. The results show thatthe gelatin-directed process is important in the formation of the ZnO nanostars, which display highphotocatalytic activity towards the degradation of methyl orange under ultraviolet (UV) irradiation.3) Hydrothermal synthesis of hollow urchin-like ZnO and its photocatalytic propertiesThis spiny urchin-like ZnO is produced at the biological template of sodium alginate underhydrothermal conditions. During the whole experiment, it is also discussed in detail that the morphology of the final product is affected by the amount of sodium alginate and ammonia, reaction temperature, and time.In addition, this ZnO structure displays a high photocatalytic activity towards the degradation of methylorange under UV irradiation.4) PVP templated synthesis of flower-like ZnO at room temperature and its photocatalytic researchThis flower-like ZnO is prepared using PVP assistant solution method at room temperature. Duringthe experiments, the amount of PVP and NaOH, stirring time and temperature affects the morphology ofthe products, which are discussed in detail. In addition, this ZnO structure displays a high photocatalyticactivity towards the degradation of Rhodamine B under UV irradiation.5) Hydrothermal in situ synthesis ZnO nanoarrays and their photocatalytic applicationsHere, single crystalline nanoarrays of ZnO have been in situ grown on cheap zinc foil inp-aminopyridine (p-APD) medium through a simple one-step hydrothermal method. The crystal featuresand morphology of the products are characterized and observed by X-ray diffraction (XRD), scanningelectron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), respectively.The possible synthetic mechanisms of the ZnO are also researched in our study. The as-prepared ZnOshows high photocatalytic ability towards the degradation of Rhodamine B under UV irradiation.