Linear sweep voltametry studies on oxygen reduction of some oxides in alkaline electrolytes

The study uses linear sweep voltametry (LSV) to observe the efficiency of oxygen reduction on some oxides and their mixtures in 6 M KOH at 25 °C. The investigated materials are Ag2O, MnO2, Sm2O3, Dy2O3 and NdO2. The electrocatalytic oxygen reduction reactions (ORR) on Teflon-bonded, oxide + graphite electrodes are studied. The oxygen reduction potentials for electrodes containing these materials as catalyst are seen as −60.67, −270.31, −111, −159.58 and −130.24 mV, respectively. Mixture combinations of these oxides give a higher ORR peak current thereby showing evidence of synergetic effect. Air–MH cells using some of the above investigated oxides as catalyst for air electrode are constructed and studied. Best performance is obtained with silver oxide. The LSV findings are in accordance with air–MH cell charge/discharge experiments and for best performance prefer shift of the ORR onset potential to more positive positions.