OXYGEN EVOLUTION REACTION ON COPPER MANGANITES - EFFECT OF PREPARATION METHOD AND ELECTRODE MANUFACTURING ON SUPERFICIAL SITES DENSITY

The importance of transition metal oxides in electrocatalysis is well known. The electrocatalytical results can be attributed to both cation ic composition of the oxide and electrode manufacturing. In order to s tudy separately the surface area effects and the intrinsic catalytic n ature, Cu1+xMn2-xO4(1.4 greater than or equal to 1 + x greater than or equal to 1) spinel oxides were synthesized by two different ways: spr ay pyrolysis and, thermal decomposition of metallic salts. The oxides obtained were characterized by means of X-ray diffraction (XRD), elect rical conductivity and pzc (pH of zero charge) measurements. Five type s of electrodes were obtained from the electrocatalytic candidate mate rial. Their electrochemically accessible surface area (easa) was deter mined using Zn2+ adsorption and kinetic measurements of a simple redox couple; results of which were in good agreement. The electrocatalytic al activity of electrode materials was evaluated studying the oer (oxy gen evolution reaction) in 1M KOH. The activity was found to be depend ent of the surface area effects and (Mn3+ + Mn4+) ions stoichiometry ( octahedrally co-ordinated with oxygen atoms in spinel structure). The possibility that information about the structure of the bulk oxide can be extrapolated to the surface is emphasized.