Graphene decorated with MoS2 nanosheets: a synergetic energy storage composite electrode for supercapacitor applications

Abstract

The two-dimensional (2D) transition metal dichalcogenide nanosheet–carbon composite is an attractive material for energy storage because of its high Faradaic activity, unique nanoconstruction and electronic properties. In this work, a facile one step preparation of a molybdenum disulfide (MoS₂) nanosheet-graphene (MoS₂/G) composite with the in situ reduction of graphene oxide is reported. The structure, morphology and composition of the pure MoS₂ and composites were comparatively analyzed by various characterization techniques. The electrochemical performance of the pure MoS₂, graphene oxide and the MoS₂/G composite electrode materials was evaluated by cyclic voltammogram, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The MoS₂/G composite showed a higher specific capacitance (270 F g⁻¹ at a current density of 0.1 A g⁻¹) compared to the pure MoS₂ (162 F g⁻¹) in a neutral aqueous electrolyte. Moreover, the energy density of the composite electrode is also higher (12.5 Wh kg⁻¹) with a high power density (2500 W kg⁻¹) compared to the pure MoS₂. In addition, the MoS₂/G composite electrode showed excellent cyclic stability even after 1000 cycles. The enhancement in specific capacitance, excellent cyclic stability and high energy density of the composite electrode are mainly due to the interconnected conductive network of the composite as well as the synergetic effect of the pure MoS₂ and graphene. The experimental results demonstrated that the MoS₂/G composite is a promising electrode material for high-performance supercapacitors.