Effect of surface layers on hydrogen entry into iron from NaOH solution during cathodic and anodic polarization

Hydrogen permeation rate (HPR) through 35-mu m Armco iron membrane at 25 degrees C was measured by the electrochemical Devanathan-Stachurski technique. It was found that cathodic and anodic polarization of the membrane in NaOH can cause an instantaneous increase of HPR. This increase was explained by acidification of the solution near the metal surface as a result of anodic oxidation of iron or cathodic reduction of iron oxides. It was suggested that porous layer of reaction products favours the increased acidification by hindering diffusion of protons from and hydroxyl ions to the metal surface. It was proposed that iron species may exert a catalytic effect on hydrogen evolution in alkaline solutions.