Electrochemical stability of Co–Mo intermetallic compound electrodes for hydrogen oxidation reaction in hot KOH solution

In order to obtain a hydrogen electrode with high-performance and stability for H2–O2 alkaline fuel cells, Brewer-type Co–Mo alloys are manufactured in the 35 to 57 wt.% Mo composition range by an arc-melting method. The electrochemical stability of alloys composed of Co3Mo and Co7Mo6 phases is investigated in hot KOH solution deaerated with N2 gas by means of electrochemical methods such as cyclic voltammetry, potentiostatic polarization and potentiodynamic polarization. Co–Mo alloy is extensively dissolved because the cobalt in alloy is soluble in hot KOH solution. The dissolution current of the alloys increases with increasing electrolyte temperature, electrolyte concentration and Mo content in the alloy.