Studies of the electrodeposition of cobalt on a vitreous carbon electrode

Experiments of cobalt deposition on a vitreous carbon electrode were carried out using cyclic voltammetry and potential steps techniques, in a sulfate medium. Cyclic voltammetry showed two stripping peaks that were attributed to the dissolution of two phases: a hydrogen rich cobalt phase and a bulk cobalt phase. Kinetic analysis of I-E response on the reverse scan for a 0.37 M of Co(II), pH 6, presented a value of -0.58 V vs. SCE for the equilibrium potential of the Co/Co(II) couple. The exchange current density was estimated as I-o = 4.8 x 10(-6) A cm(-2) in this solution. Potential step experiments showed that the cobalt deposit on vitreous carbon is formed by a mechanism of progressive nucleation followed by 3-D growth. Both techniques confirmed that cobalt deposition takes place in two single electron steps.