Preparation And Characterization Of Oxides(Hydroxides) Nano(Micro) Crytals

In this dissertation, hierarchical structureα-Ni(OH)₂ microspheres, ZnOnanopartMes and flowerlike ZnO, MnO₂ nanoparticles and nanoflakes had beenprepared by liquid-phase methods.1. Ni(OH)₂ microspheres with hierarchical structure were prepared by reaction ofNiSO₄·6H₂O and urea at 150℃C for 2.5 h through hydrothermal method. Themorphologies and the structures of the samples were characterized using XRD andSEM. It has been found that the as-synthesized sample wasα-Ni(OH)₂. The SEMobservation results indicated thatα-Ni(OH)₂ microspheres of 1-3μm in diameter wereconstructed withα-Ni(OH)₂ nanosheets and showed hierarchical structure. Thethickness of Ni(OH)₂ nanosheets was in the range of 1-10nm. The influence of variousexperimental conditions on the reaction has been investigated in detail. The specificsurface area of Ni(OH)₂ microspheres obtained by hydrothermal process was 157.27m²Â·g^-1. And the sample obtained by refluxing method has specific surface area of 31.29m²Â·g^-1. The electrochemical property of the sample was obtained through cyclicvoltammetry method.2. ZnO nanoparticles and flowerlike structure were prepared by reaction ofZn(NO₃)₂ and NaOH in the refluxing media of glycol and water at 150℃for 2.5 h.The morphologies and the structures of the samples were characterized using XRD andSEM. The SEM observation results showed that ZnO nanoparticles were uniform in size and have a diameter range of 20-50 nm. The flowerlike structures of 1μm indiameter were constructed with ZnO Nanosheets. The thickness of ZnO nanosheetswas in the range of 80-120 nm.3. MnO₂ nanoparticles and nanoflakes were. prepared by reaction of KMnO₄ andMnSO₄ in the refluxing media of glycol and water at 140℃for 2.5 h. Themorphologies and the structures of the samples were characterized using XRD andTEM. The TEM observation results displayed that MnO₂ nanoparticles were uniformin size, and the diameter is in the range of 100-200nm. The specific surface area ofMnO₂ obtained by refluxing method was 49.48 m²Â·g^-1.