Hydrothermal microemulsion synthesis of cobalt nanorods and self-assembly into square-shaped nanostructures

In this work, we present hydrothermal microemulsion as a novel technique to synthesize cobalt nanorods with hcp structure at a relatively low temperature. The average size of the Co nanorods synthesized for 15 h is about 10 nm in diameter and 260 nm in length. These nanorods could spontaneously self-assemble into two-dimensional (2D) square-shaped frames or dense multilayer nanosquares assisted by a magnetic field. The formation process and the corresponding mechanism of the novel self-assembled nanostructures are discussed.