Electrodeposition of Catalytically Active Cobalt Powder from Aqueous Sulfate Electrolytes

Abstract

Abstract The electrodeposition of cobalt powder was investigated from aqueous sulfate solutions containing 0.0125–0.0500 CoSO4·7H2O (I), 0.23–1.00 (NH4)2SO4 (II), 0.1 H3BO3 and 0.07 mol dm−3 Na2SO4·10H2O. The effects of the bath composition, the pH, the deposition current density and the duration of electrolysis on the cathodic polarization and the efficiency of cobalt electrodeposition, as well as on the morphology and the catalytic activity (towards the decomposition of 0.4% H2O2 solution) of the as-deposited cobalt powders were discussed. X-Ray diffraction studies proved that cobalt powders were very pure and deposited in the hexagonal close-packed structure with the orientations (100), (002), and (101). Cobalt powder deposited with an efficiency of 32% and had a catalytic activity approaching 100% could be obtained from the above-mentioned bath formula containing 0.05 mol dm−3 (I) and 0.46 mol dm−3(II). The optimum operation conditions to achieve these characteristics were: pH 4.78, j=10A dm−2 and t=15 min.