Fabrication of Cobalt Nanowires by Electroless Deposition under External Magnetic Field

Metallic Co nanowires with a mean diameter of about 190 nm and lengths up to 160 µm are prepared by electroless deposition (solution reduction) in propylene glycol at room temperature under external magnetic field. Co deposition behavior in propylene glycol is investigated by in situ monitoring of mixed potentials in conjunction with linear sweep voltammetry and the oxidation-reduction potential of the Co(II)/Co redox pair is determined to be about −0.54 V vs Ag/AgCl. When the mixed potential drops below the oxidation-reduction potential of the Co(II)/Co redox pair, small Co nanoparticles are generated in the solution and are magnetized in the presence of external magnetic field. Strong attractive dipolar interactions are induced along the magnetic field direction, which results in the assembly of Co nanoparticles to nanowires. The Co nanowires exhibit ferromagnetic properties at room temperature, with an enhanced coercivity of about 700 Oe possibly due to shape anisotropy.