Morphology-controlled synthesis of octahedron and hexagonal plate of Co3O4

Hexagonal plate-like Co3O4 was prepared by the thermal oxidation of a Co(OH)2 precursor with a hexagonal plate morphology at 600A degree C in air. The Co(OH)2 precursor was obtained by hydrothermal synthesis from CoCl2, KCN and hydrazine at 180A degree C. The hexagonal plates had a side length of approximately 3.5I14m and 1I14m in thickness. Octahedral Co3O4 was prepared by a hydrothermal method with CoCl2, KCN, and H2O2 at 180A degree C. H2O2 played an important role in the formation of Co3O4 with an octahedral morphology. A hierarchical hexagonal skeleton-like morphology assembled with small octahedral Co3O4 particles was also prepared using a hydrothermal method with CoCl2 and KCN. The mechanism of the morphology-controlled synthesis of Co3O4 is discussed.