Preparation and electrochemical characterization of spinel type Fe–Co3O4 thin film electrodes in alkaline medium

Spinel type Fe–Co3O4 (0, 5 and 10% of Fe) adherent and stable films have been prepared on stainless steel supports using the thermal decomposition method at 400 °C. All the oxides prepared by this method produced the pure spinel phase. The electrochemical characterization of the catalytic films towards O2-evolution has been made using cyclic voltammetry and ac impedance techniques. The data show that the partial replacement of Co-ion by Fe-ion in the cobalt cobaltite Co3O4 leads to electrodes with lower surface areas. On the other hand, an enhancement of the electrocatalytic activity, towards the oxygen evolution, is confirmed by the values calculated for the corrected Tafel slopes. Values ranging from 71 to 44 mV were obtained for the pure and iron containing oxides.The reaction order with respect to OH− concentration was found to be ∼1 on pure and ∼2 on the substituted oxides.