In situ fabrication of graphene decorated microstructured globe artichokes of partial molar nickel cobaltite anchored on a Ni foam as a high-performance supercapacitor electrode

Abstract

By taking advantage of the splendid properties of graphene (electrical conductivity) and transition metal oxides (pseudocapacitance nature), we have in situ fabricated novel microstructured globe artichokes of a rGO/Ni_0.3Co_2.7O₄ composite on a nickel foam through a simple surfactant free hydrothermal method followed by calcination process. The globe artichoke flower-like morphology is constructed by hundreds of self-assembled micropetals interconnected with several layers and circles at the base to form microspheres of uniform dimension. The as-obtained morphology of the microstructured globe artichokes enhanced the stability and electrochemical performance of the hybrid electrode due to of its unique structure. Therefore, the synergetic effects and interconnected structure of the thus made binder free rGO/Ni_0.3Co_2.7O₄ hybrid electrode allows better charge transport and exhibits superb specific capacitance and areal capacitance of 1624 F g⁻¹ and 2.37 F cm⁻² at a current density of 2 A g⁻¹. Moreover, the specific capacitance increases from 1088 F g⁻¹ to 1728 F g⁻¹ at the end of 7000 cycles, which indicates that the material becomes active with cycling. Furthermore, when the power density increased by 16 times i.e. from 0.5 to 8 kW kg⁻¹ the energy density sinks to 40 from 56.39 W h kg⁻¹ (i.e., 29% reduction only), suggesting a remarkable electrochemical performance for supercapacitor applications.