Electrochemical Dissolution of Co3O4 in Acidic Solutions

The cyclic voltammetry method was used to study the regularities of the electrochemical behavior of cobalt cobaltite in an acidic medium. It is shown that cathodic reduction of Co3O4 in the studied range of potentials of + 1.0 to - 0.8 V is a multistage process occurring according to the scheme: Co3O4+delta ->(I) Co3O4-delta ->(II) CoO ->(III) Co-0. In the following anodic half-cycle, formation of the CoO protoxidic phase is continued from such sources as Co3O4-delta and metallic cobalt. At the potentials to the positive of + 0.25 V, the process of absorption of the superstoichiometric oxygen is realized within the region of homogeneity of the CoO1+delta protoxidic phase. The dependence of the rate of the chemical stage of the process on the potential sweep direction and also a significant increase in the rate of stage II at the second and further electrode polarization cycles was explained within the theory of nucleation and diffusion of charged particles in the electric field.