Effect of Co3O4 on the structure and electrochemical performance of IrO2-Co3O4/Ti electrodes by first-principles calculations and experimental

Abstract

The electrode materials have a decisive effect on the performance of supercapacitors. IrO2-Co3O4/Ti composite material was prepared by a thermal decomposition method. The first-principles calculation was used to study the effect of Co content on the electronic structure of IrO2-Co3O4. The influence of the Co3O4 content on the microstructure and electrochemical performance of the electrode was analyzed in detail. First-principles calculation revealed that the coating with the 50% mol Co3O4 was in a full conductive structure, and the density of states of the composite oxide with excessive content of Co3O4 would shift to a higher energy level and generate a band gap. Co doping could inhibit the crystallization of IrO2. The 50%IrO2-50%Co3O4/Ti electrode exhibited the most obvious coexistence of crystalline and amorphous phases. Besides, the addition of Co3O4 changed the microstructure to a ring-shaped branched structure, which effectively increased the specific surface area and total pore volumes of the coating. The electrode with the 50% Co3O4 had the maximum capacitance value of 979.6 F/g and maintained 90% of its initial capacitance even after 20,000 cycles of constant charge-discharge cycles, which was an ideal electrode material for supercapacitors. The results from first-principles calculation and the experiments were in consistency.