Enhanced performance of supercapacitor electrode materials based on hierarchical hollow flowerlike HRGOs/Ni-doped MoS2 composite

Abstract Hollow reduced graphene oxide spheres/nickel-doped molybdenum disulfide (HRGOs/Ni-doped MoS2) composites with hierarchical hollow flowerlike structure have been synthesized via electrostatic self-assembly and one-step hydrothermal method. It is found that the HRGOs/Ni-doped MoS2 composites exhibit excellent electrochemical performance. Especially, HRGOs/Ni-doped MoS2-5 composite prepared with 0.15 mmol nickel nitrate (Ni(NO3)2·6H2O), displays high specific capacitance (544 F g−1 at a current density of 1 A g−1), excellent cycle stability (91.2% of capacity retention after 2500 cycles at a current density of 1 A g−1)and enhanced rate capability (60% of capacity retention as scanning rate increases from 5 to 100 mV/s). These can be ascribed to the important role playing by rational Ni doping and a nice hierarchical hollow flowerlike structure. Theoretical calculations revealed that Ni doping into MoS2 not only greatly modifies its electronic structure but also creates rich activated S, Mo and Ni atoms, which can cast significant influence on the electrochemical performance. Meanwhile, hierarchical hollow flowerlike structure optimizes the exposure of electrochemical active sites, shortens the diffusion distance of electrolyte ions and alleviates the volume change during charge/discharge cycle process of the composite. Therefore, HRGOs/Ni-doped MoS2 composite can be considered as an appealing electrode material for supercapacitors.