Metal Oxide Catalysts for the Evolution of O2 from H2O

Abstract

This paper describes an iron-nickel oxide catalyst that can eliminate oxygen overvoltage in the electrolysis of alkaline water. Oxygen overvoltage is the largest source of energy loss in water electrolysis. A method for cathodic electrodeposition of first-row transition metal oxides for use as catalysts is described, and the effects of the electrodeposition variables on catalytic performance and catalyst composition were explored. The NiFe oxide catalyst achieved a nearly ideal anodic electron-transfer coefficient, αa = 0.0082 (14.8 mV/decade) in a 1 M KOH solution. The metal oxide catalysts reported here could produce hydrogen and oxygen from water at approximately the thermodynamic potential for small currents. Both transmission electron microscopy and X-ray photoelectron spectroscopy experiments indicated that the NiFe oxide was composed of small crystals (∼1 nm) connected with an amorphous phase and contained a highly disordered arrangement of all nonmetallic nickel and iron oxidation states. Changes ...