Synthesis of hierarchical hollow urchin-like HGRs/MoS2/MnO2 composite and its excellent supercapacitor performance

Abstract

Hierarchical hollow urchin-like ternary composite which consists of hollow graphene spheres(HGRs), flowerlike molybdenum disulfide(MoS2) and manganese dioxide(MnO2) nanoflakes has been successfully synthesized by chemical vapor deposition(CVD) and two-step hydrothermal methods. The HGRs/MoS2/MnO2 composite was characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM) and transmission electron microscopy(TEM), and its electrochemical properties were evaluated by cyclic voltammetry(CV), galvanostatic charge/discharge(GCD), and electrochemical impedance spectroscopy(EIS) measurements. The experimental results demonstrated that the specific capacitance of HGRs/MoS2/MnO2 composite is 608 F g−1 at a current density of 1 A·g−1, which is far higher than that of HGRs/MoS2 (300 F g−1) and HGRs/MnO2 (344 F g−1). In addition, 89.3% of the original capacitance of HGRs/MoS2/MnO2 composite is retained after 2500 cycles at a current density of 2 A·g−1, which keeps better cycle stability compared to HGRs/MnO2 composite. The excellent electrochemical performance can be ascribed to the synergistic effect of HGRs, flowerlike MoS2 and MnO2 nanoflakes. Flowerlike MoS2 as an ion buffer layer is beneficial to rapid ion diffusion and transportation from MnO2 into interior HGRs. Furthermore, HGRs/MoS2 composite as a three-dimensional(3D) matrix alleviates the volume change during charge/discharge cyclical process. The well-structured HGRs/MoS2/MnO2 composite with high performance has a great potential for advanced supercapacitors(SCs) applications.