THIN-FILMS OF CO3O4 AND NICO2O4 PREPARED BY THE METHOD OF CHEMICAL SPRAY PYROLYSIS FOR ELECTROCATALYSIS .4. THE ELECTROCATALYSIS OF OXYGEN REDUCTION

An electrode kinetic study of the electroreduction of oxygen has been made on thin films of Co3O4 and NiCo2O4 in alkaline medium. E-log i curves on these films indicated two Tafel slopes which were close to - RT/F and - 2RT/F in the low and high current density regions, respectively. The reaction showed one-half order kinetics in [OH-] at low current densities and nearly zero-order at higher current densities. The reaction order with respect to the partial pressures of oxygen was found to be unity. Based on these results, a common mechanism for oxygen reduction involving the electroreduction of physisorbed molecular oxygen forming the peroxide radical as the rate-determining step has been suggested.