Construction of cobalt sulfide/graphitic carbon nitride hybrid nanosheet composites for high performance supercapacitor electrodes

Two-dimensional hybrid nanostructures have recently received great interest in the construction of supercapacitor electrodes due to their unique structural features. In this work, novel cobalt sulfide/graphitic carbon nitride (g-C3N4/CoS) hybrid nanosheet composite have been prepared by anchoring CoS nanosheets on the surface of g-C3N4 through a simple solvothermal method. The g-C3N4/CoS nanosheet-on-nanosheet composites exhibit excellent electrochemical performance as electrode for supercapacitors. It is found that the g-C3N4/CoS hybrid nanosheet composite electrode achieves a high specific capacitance of 668 F g−1 at a current density of 2 A g−1. Moreover, the electrode shows good long-term cyclic stability without obvious capacitance decreases after 5000 cycles. The superior properties in specific capacitance and cycling stability can be ascribed to the nanosheet heterostructure which provides high surface area, short transport distance of the ions and strong interfacial interaction, facilitating fast electron-ion transport and improving structure stability of the composite.