Facile synthesis of leaf-like cobalt microstructures at low temperature

Three-dimensional (3D) hierarchical cobalt microstructures with a leaf-like shape were prepared using cobalt chloride as the starting material via a facile solution method at 90°C. An ethanol and water mixed solution was used as the solvent, and hydrazine was employed as the reducing agent. The phase purity and morphologies were investigated by X-ray diffraction and scanning electron microscopy. It was found that the concentration of alkaline and the volume ratio of ethanol to water played important roles for the shape control of the final products. Magnetisation measurements revealed that the leaf-like cobalt microstructures exhibited ferromagnetic characteristics with a saturation magnetisation of 156.2 emu/g and an enhanced coercivity of 371.5 Oe at room temperature. This relatively simple, efficient and shape controllable approach can be extended to the preparation of other metal materials with complex 3D micro/nanostructures.