Control Of ZnO Morphology And Their Photocatalytic Performance

ZnO is considered to be one of the most promising photocatalysts among various semiconductors with a wide band-gap of 3.37 eV and a large exciton binding energy of 60 meV. The photocatalytic properties of ZnO are strongly dependent on its structures, including the morphology, aspect ratio, crystallite dimension, and orientation of crystal. Therefore, it is necessary for change ZnO photocatalytic activity by adjusting the reaction conditions to prepare the different morphology of zinc oxide, its catalytic performance for change is also necessary.The first part of work is by adopting hydrothermal method, adjusting raw materials dosage and adding different content of surfactant(sodium citrate), dropping with different amount of ammonia, and we did adjust for the hydrothermal of time and temperature to control the morphology of ZnO precursor. To explore the effect of these experimental parameters on the morphology of ZnO precursor and through the scanning electron microscope(SEM) to observe the morphology of ZnO precursor.Another important work, the surfactant-free hydrothermal method without using any crystal seeds, environmentally harmful chemicals, or severe reaction conditions has been developed to fabricate porous rectangular ZnO nanosheets. Various morphologies, such as ultralong doubleended needle-like ZnO and polycrystalline hexagonal ZnO microrods, were firstly obtained by tuning only the concentration of Zn(Ac)2·2H2O and CO(NH2)2. The morphological evolution of these samples depending on hydrothermal time and the concentration are investigated to shed new light on the formation condition of several morphologies. Moreover, the morphology-dependent photocatalytic performances were explored, which shows that the porous rectangular ZnO nanosheets exhibit the highest photocatalytic activity among these ZnO samples with different morphologies.