On the mechanism of oxygen reduction on single-crystal and polycrystalline Pt electrodes in alkaline media

The characteristics of oxygen reduction on various platinum electrodes (smooth polycrystalline metal, Pt(hkl) single-crystals, disperse materials) in alkaline media are interpreted. The interpretation was based on the theory of electrochemical processes with a slow subsequent heterogeneous reaction. The dependence of polarization curve slopes in Tafel coordinates on the type of electrode material surface is explained based on the Temkin approach as the energetic inhomogeneity of the electrode surface. The energetic inhomogeneity is associated with the appearance of surface hydroxide nanoclusters of various composition based on oxidized platinum atoms which simultaneously represent the surface lattice defects s, dPt. The multistage heterogeneous chemical reaction is interpreted as the innercluster oxidation of the previously electrochemically reduced s, dPt atoms by oxygen molecules.