Oxygen reduction behavior with silver alloy catalyst in alkaline media

The electrochemical characteristics of silver catalyst impregnated on carbon black at the oxygen electrode for an alkaline fuel cell were studied. The electrode containing 30 wt.% silver catalyst showed a current density equivalent to that of Pt catalyst. To improve the catalytic activity and electrode performance, silver was bimetallized with Mg and the alloy state was confirmed by X-ray diffraction. When the atomic content of Ag-Mg alloy was 3:1, it showed the highest current density. A decrease in the corrosion potential at the electrode was found by the catalytic effect of silver. The contact of carbon and silver caused a decrease in the reaction sites of silver and the electrolyte, and hence the dissolution potential of silver was increased. Because the fuel cell was operated at an overpotential of 100-300 mV, the dissolution of silver was not important.