Synthesis of Hollow Hexagonal Nickel-Cobalt Sulfide/RGO Nanocomposite for Supercapacitor Application

The uniform nanocomposites of hollow hexagonal nickel-cobalt sulfide/reduced graphene oxide (HHNCS/RGO) are synthesized through a two-step hydrothermal route, and they were characterized by XRD, SEM, TEM and Raman. It is found that nickel-cobalt sulfides with hollow hexagonal structure were uniformly anchored on the surface of RGO sheets. The as-prepared nanocomposites as supercapacitor electrodes present good electrochemical performances. The HHNCS/RGO nanocomposites deliver a maximum specific capacitance of 927 F.g(-1) at the current density of 1 A.g(-1), and still exhibit a high specific capacitance of 724 F.g(-1) at the big current density of 20 A.g(-1), indicating their good rate capability. In addition, the specific capacitance retains 93% of its initial value after 2 000 charge-discharge cycles at the current density of 5 A.g(-1), indicating their high cycling stability. The enhanced capacitive performance is attributed to the fact that RGO can not only improve the conductivity of HHNCS/RGO nanocomposites but also work as support to disperse the HHNCS nanosheets effectively.