TRANSITION-METAL OXIDES BASED OXYGEN ELECTRODES IN ALKALINE-SOLUTION - ELECTROCATALYSIS BY SOME PEROVSKITE OXIDES BASED ON MANGANESE AND COBALT

The electrocatalysis of oxygen electrode reactions by rare earth element (such as fanthanum and dysprosium) based manganates and cobaltates obtained through thermal methods in selected non-stoichiometric compositions, has been investigated in KOH solutions. The effects of partial substitution of Ca/Ba/Sr in definite stoichiometry on the electrocatalytic behaviour of LaMnO3 have been reported. It has been observed that the oxygen reduction occurs by dissociative chemisorption route on these electrodes at low overpotentials. At higher overpotentials, formation of H2O2 occurs. The electrochemical parameters for the oxygen evolution reaction on these electrocatalysts have been obtained under common alkaline water electrolysis conditions with a view to assess their possible application as anodes. It has been found that the overpotential contribution by the anode to the electrolyser voltage can be reduced by 0.1-0.15 V when compared with the conventional nickel anodes.