ACTIVE THIN NICO2O4 FILM PREPARED ON NICKEL BY SPRAY-PYROLYSIS FOR OXYGEN EVOLUTION

Thin films of NiCo2O4 were prepared on Ni at 370 degrees C by the method of spray pyrolysis. The films were uniform, adherent, free from cracks and electrocatalytically much more active for oxygen evolution than other NiCo2O4 films recently reported in the literature. This film electrode showed two Tafel slopes similar to 40 and similar to 120 mV decade(-1) at low and high overpotential, respectively. The second-order observed kinetics in OH- concentration at lower overpotentials changed to first-order at higher overpotentials. A suitable mechanism involving the formation of a physisorbed hydrogen peroxide intermediate in a slow electrochemical step has been suggested.