超临界二氧化碳体系中正八面体氧化钴颗粒的生长及其表征

研究了正八面体氧化钴颗粒在超临界二氧化碳体系中的合成过程。在密闭的不锈钢高压反应釜中，1.0 g乙酸钴和12.0 g干冰在450 ℃下，反应12 h后合成粒径大约10 μm的正八面体氧化钴颗粒。通过XRD、 XPS、TEM、 SEM以及拉曼光谱的分析，氧化钴颗粒是由八个{111}面包裹着的正八面体单晶组成。条件实验显示，超临界二氧化碳体系是正八面体氧化钴颗粒合成的充分条件。其生长机理可能是：乙酸钴在超临界二氧化碳体系中的热分解；氧化钴的结晶和定向缓慢生长。在性能方面，初步研究了正八面体氧化钴颗粒在作为锂离子电池电极材料的应用。

Growth and Characterization of Octahedral Cobalt Oxide Particles in Supercritical Carbon Dioxide System

The synthesis of regular octahedron cobalt oxide microcrystals for the application of battery material in supercritical carbon dioxide system was studied. Regular octahedron microcrystals of cobalt oxide with a size about10 μm were prepared at 450℃ in a closed vessel consisting of 1.0 g of cobalt acetate powder and 12.0 g of dry ice. The as-obtained particles were charterized by XRD, XPS, SEM, TEM and Raman spectroscopy techniques. The XRD and Raman spectroscopy results indicate that the crystal structures of the particles (the cobalt oxide microcrystals) are inerratic. SEM and TEM results reveal that the morphology of cobalt oxide microerystals appear to be the regular octahedron enclosed by eight {111} facets. It is found that the supercritical carbon dioxide system is a full condition to the synthesis of regular octahedron cobalt oxide. The size of cobalt oxide microcrystals increases with reaction time and the morphology is temperature dependent. The possible growth mechanism of regular octahedron cobalt oxide microcrystals was discussed based on the pyrolysis of cobalt (111) acetate, crystallization of cobalt oxide and Slowly Orientational Growth (SOG) due to anisotropy in supercritical carbon dioxide environment at reaction temperatures. The charge/discharge properties of regular octahedron microcrystals of cobalt oxide used as battery material wereal so characterized and discussed.