Effect of the Co3O4 introduction in the pseudocapacitive behavior of IrO2-based electrode

A new electrode based on Ir-2 + Co3O4 (30:70 mol %) composition has been pr epared by thermal decomposition (400 degreesC) from mixtures of chloride pr ecursors and characterized by energy dispersive X-ray, scanning electron mi croscopy, X-ray diffraction analysis, cyclic voltammetry, and charging/disc harging curves. The electrochemical behavior shows dependence on the cathod ic potential limit employed, and a good potential window (1.4 V) in aqueous NaOH and high electrocatalytic area due to the contribution of different r edox transitions of Ir and Co surface sites. The electrode has been found t o perform as superior electrodes in electrochemical capacitor applications with a specific capacitance of 500-600 F g(-1). The large capacitance exhib ited by this system arises from a combination of the double layer capacitan ce and pseudocapacitance associated with surface redoxtype reactions. (C) 2 001 The Electrochemical Society.