Activation of the Iron Surface to Hydrogen Absorption Resulting from a Long Cathodic Treatment in NaOH Solution

Electrochemical measurements of the permeation rate of hydrogen through pure iron cathodically polarized in , together with ellipsometric and optical observations of the electrode surface, were performed. A long, uninterrupted charging caused disintegration of a subsurface metal layer and, as a result, the metal surface became more prone to both hydrogen absorption and corrosion. The permeation rate through activated iron membranes was controlled by the cathodic current density. An addition of EDTA into increased the activity of the iron surface by removing from it some oxidized products of the chemical reaction of iron with water. Therefore, at the same charging current density, the hydrogen permeation rate through iron membranes was much greater in the presence than in the absence EDTA. On the contrary, a layer of palladium on the input surface impeded the entry of hydrogen.