One-step synthesis of Ni₃S₂ nanorod@Ni(OH)₂ nanosheet core-shell nanostructures on a three-dimensional graphene network for high-performance supercapacitors

A three-dimensional graphene network (3DGN) grown on nickel foam is an excellent template for the synthesis of graphene-based composite electrodes for use in supercapacitors. Ni(OH)₂ nanosheets coated onto single-crystal Ni₃S₂ nanorods grown on the surface of the 3DGN (referred to as the Ni₃S₂@Ni(OH)₂/3DGN) are synthesized using a one-step hydrothermal reaction. SEM, TEM, XRD and Raman spectroscopy are used to investigate the morphological and structural evolution of the Ni ₃S₂@Ni(OH)₂/3DGN. Detailed electrochemical characterization shows that the Ni₃S₂@Ni(OH) ₂/3DGN exhibits high specific capacitance (1277 F g^-1 at 2 mV s^-1 and 1037.5 F g^-1 at 5.1 A g^-1) and areal capacitance (4.7 F cm^-2 at 2 mV s^-1 and 3.85 F cm^-2 at 19.1 mA cm^-2) with good cycling performance (99.1% capacitance retention after 2000 cycles).