Corrosion Resistance of Co77Si11B12 Amorphous Metal Alloys for the Electrodes of Hydrogen Release from Alkaline Solutions

We study the corrosion resistance of an amorphous cobalt-based alloy (AMA) by the method of cyclic voltammetry (VA) in a 1 M KOH aqueous medium at different temperatures varying from 293 to 333°K. It is shown that, as a result of fivefold cyclic polarization of electrodes within the range from – 1.5 to + 0.5 V, the corrosion potential shifts to the cathodic side and, in solutions with temperatures of 313–333°K, takes almost identical values. The corrosion current density in AMA becomes eight times higher as the temperature of solution increases to 313°K. The corrosion resistance of AMA used in the reaction of hydrogen release becomes higher as follows from the values of current density that are twice lower than for the alloys in the intact state. The computed values of corrosion activation energy are equal to 18.65 and 17.86 kJ/mole for the first and fifth cycles of the VA curve, respectively. This corresponds to the diffusion-controlled interaction of hydroxyl ions with the surfaces of AMA electrodes. We computed the activation energy of formation of compounds on the AMA surface. It was established that the [Co–O–H2O]ads chemisorbed complex is formed with a twice higher activation energy than the passivating layers.