The integration of 2 D graphene nanosheets and layered transition-metal dichalcogenides has been recognized as one of the most extensive strategies for the synthesis of promising electrode materials for energy-storage devices. In this study, cubic manganese diselenide (MnSe 2 ) and hybrid reduced graphene oxide/MnSe 2 (G-MnSe 2 ) materials were synthesized by a facile hydrothermal method. Metallic selenium impurities are considered to be a major unwanted byproduct in this method. An effective means to remove such bulk chalcogenides is a key challenge. For the synthesis of the G-MnSe 2 hybrid material, we used a strategy in which the graphene oxide was mixed with manganese and selenium precursors. Surprisingly, the final G-MnSe 2 product contained a negligible amount of selenium impurity. The MnSe 2 and G-MnSe 2 hybrid materials were characterized in detail. For the first time, the electrochemical energy-storage behavior of MnSe 2 -based materials was assessed for supercapacitor applications. The specific capacitance of the MnSe 2 electrode was approximately 57.8 mF cm −2 , whereas the hybrid G-MnSe 2 electrode showed a much higher specific capacitance of 93.3 mF cm −2 at a scan rate of 1 mV s −1 . A symmetric cell made from the G-MnSe 2 hybrid material showed excellent long-term stability for 4500 cycles and approximately 106 % retention of its initial capacitance, which is impressive compared with the cycle life of the MnSe 2 -based symmetric cell (80 % capacitance retention at the 4500th cycle).
- hydrothermal synthesis
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