ELECTROCHEMICAL STUDIES ON PROTECTIVE THIN CO3O4 AND NICO2O4 FILMS PREPARED ON TITANIUM BY SPRAY PYROLYSIS FOR OXYGEN EVOLUTION

Electrochemical studies were done on thin Co3O4 and NiCo2O4 films on Ti by cyclic voltammetric and potentiostatic polarization techniques. The films were quite conductive and prevented the underlying surface from playing a harmful role during measurements. The results indicated the formation of a surface quasi-reversible redox couple, CoIV/CoIII, in KOH solution. The reaction order with respect to OH− ion concentration was found to be nearly 2. The Tafel slopes decreased with increasing KOH concentrations. NiCo2O4 was observed to evolve oxygen gas at a lower overpotential as compared to that of Co3O4. Electrode kinetic parameters suggest similar mechanisms for the oxygen evolution for both the oxides. © 1990, The Electrochemical Society, Inc. All rights reserved.