Electrochemical Stability of Co-Mo and Ni-Mo Intermetallic Compound Electrodes for Hydrogen Electrode of Alkaline Fuel Cell

Abstract

The Electrochemical stabilities of the Brewer-Engel type intermetallic compounds of Co-Mo and Ni-Mo manufactured by the arc-melting method for the hydrogen electrode of alkaline fuel cell were investigated. Effects of temperature and concentration on the electrochemical behavior of the electrodes in the 6 N KOH solution deaerated with gas were studied by electrochemical methods. The effect of overpotential on the electrochemical stabilities of Co-Mo and Ni-Mo intermetallic compounds was also discussed under the normal operation condition of AFC. It was shown that Co-Mo electrode had lower electrochemical stability as compared to Ni-Mo. In the case of Co-Mo electrode, a simultaneous dissolution of cobalt and molybdenum has occurred at low anodic overpotential form equilibrium hydrogen electrode potential, but the dissolution of cobalt was serious, and Co(OH)l layer on the electrode surface formed at the high anodic overpotential. In contrast the Ni-Mo electrode had high electrochemical stability because formation of the dense and thin protective layer prevented the dissolution of molybdenum.