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

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.