ELECTRODE-REACTIONS ON DEMETALIZED SURFACES

Many electrode reactions occurring nominally on metals proceed in fact on a demetalized surface produced by formation of a semiconducting surface reaction film on the electrode. A viewpoint is presented that in these cases of electrode reactions, the electrode kinetic behavior should be interpreted in terms of solid-state surface properties (especially the bandgap and thence semiconductivity and solid-state cohesion) of the surface film rather than the electronic properties of the underlying metal. Equations are formulated to take this into account and the considerations developed provide a basis to interpret a large amount of literature data on the following subjects: oxygen reduction reaction; oxygen evolution reaction; anodic dissolution of metals in anhydrous hydrogen fluoride and in sulfamic acid-formamide solutions; Fe(CN)//6**4**-/Fe(CN)//6**3**- reaction on platinum, oxide films, and oxides; and possibly the open-circuit corrosion potentials of some common metals.