Silver cathodes, oxygen reduction alkaline electrolyte

G. Silver Cathodes for Oxygen Reduction in Alkaline Electrolyte... 

However, for technical use of AFC, the long-term behavior of AFC components is important, especially that of the electrodes. Nickel can be used for the hydrogen oxidation reaction (catalyst in the anode) and on the cathode silver can be used as catalyst (see next section), no expensive noble metal (platinum) is necessary, because the oxygen reduction reaction kinetics are more rapid in alkaline electrolytes than in acids and the alkaline electrochanical environment in AFC is less corrosive compared to acid fuel cell conditions. Both catalysts and electrolyte represents a big cost advantage. The advantages of AFC are not restricted only to the cheaper components, as shown by Giilzow [1996]. 

The reduction of molecular oxygen that is supplied either directly from containers or in a diluted form as air constitutes the reaction at the cathode in fuel cells. The use of air is preferable for economic reasons. Platinum metals and alloys of platinum metals are electrocatalysts for acid and alkaline electrolytes. Silver, silver alloys, nickel, carbon, and intermetallic compounds represent less expensive electrocatalysts for the oxygen electrode in alkaline solutions. In contrast to the hydrogen electrode, the overvoltage of the oxygen electrode is large at temperatures below 100 °C when a reasonable current is drawn. 

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