Fabrication of ultrathin CoMoO4 nanosheets modified with chitosan and their improved performance in energy storage device

Abstract

Ultrathin nanosheet-assembled cobalt molybdate (CoMoO₄) with a mesoporous morphology was synthesized by a urea-assisted solution combustion route at a temperature of 400 °C. The as-prepared CoMoO₄ was modified using chitosan cross-linked with glutaraldehyde (glu) and employed as a cathode material in an aqueous hybrid capacitor. The physical and electrochemical behaviour of CoMoO₄ modified with chitosan and the as-prepared (chitosan free) CoMoO₄ has been compared and discussed. The modified CoMoO₄ exhibited excellent electrochemical performance with a specific capacitance of 135 F g⁻¹ at 0.6 A g⁻¹ and an energy density of 31 W h kg⁻¹. It also exhibited good cycling stability with high coulombic efficiency over 2000 cycles retaining a specific capacitance of 81 F g⁻¹ at 3 A g⁻¹, comparatively much better than that of nanostructured chitosan free CoMoO₄ which yielded 17 F g⁻¹. The results indicated that chitosan gel strongly adheres to the molybdate moiety of CoMoO₄ and increases the capacitance four-fold compared to a chitosan free material. The modified CoMoO₄ electrode shows potential for high performance, and is an environmentally friendly and low-cost energy storage device.