Electro-Catalytic Activity of RuO2-IrO2-Ta2O5 Mixed Metal Oxide Prepared by Spray Thermal Decomposition for Alkaline Water Electrolysis

Oxygen evolution reaction for alkaline water electrolysis was studied using various mixed metal oxide catalysts. Mixed metal oxide electrodes consisting of RuO2, IrO2, and Ta2O5 with various ratios on a titanium substrate were prepared by spray thermal decomposition. The crystallinity of the synthesized catalyst was investigated via X-ray diffraction, and the oxidation state of each component was determined using X-ray photoelectron spectroscopy (XPS). Surface morphology was investigated by scanning electron microscopy, and the roughness factor was determined by cyclic voltammetry (CV) in 1 M H2SO4. Electo-catalytic activity for oxygen evolution reaction was measured by cyclic voltammetry (CV) in 1 M KOH at room temperature, and it was found to be strongly dependent on composition of catalyst. Among all electrodes tested, catalyst with a composition of Ru:Ir:Ta= 1:2:2.5 exhibited the highest current density of 100 mA cm(-2) at 1.67 V, corresponding to an overpotential of 0.44 V.