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 600 degrees C in air. The Co(OH)(2) precursor was obtained by hydrothermal synthesis from CoCl2. KCN and hydrazine at 180 degrees C. The hexagonal plates had a side length of approximately 3.5 mu m and 1 mu m in thickness. Octahedral Co3O4 was prepared by a hydrothermal method with CoCl2, KCN, and H2O2 at 180 degrees 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. (C) 2010 Elsevier B.V. All rights reserved.