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 prepared by thermal decomposition (400 degreesC) from mixtures of chloride precursors and characterized by energy dispersive X-ray, scanning electron microscopy, X-ray diffraction analysis, cyclic voltammetry, and charging/discharging curves. The electrochemical behavior shows dependence on the cathodic potential limit employed, and a good potential window (1.4 V) in aqueous NaOH and high electrocatalytic area due to the contribution of different redox transitions of Ir and Co surface sites. The electrode has been found to perform as superior electrodes in electrochemical capacitor applications with a specific capacitance of 500-600 F g(-1). The large capacitance exhibited by this system arises from a combination of the double layer capacitance and pseudocapacitance associated with surface redoxtype reactions. (C) 2001 The Electrochemical Society.