NiSe@MoSe Nanosheet Arrays as the Electrode for High-Performance Supercapacitors.

In this study, we report novel NiSe@MoSe nanosheet arrays prepared by a facile one-step hydrothermal method through nickel (Ni) foam as Ni precursor and the framework of MoSe. Owing to the unique interconnection and hierarchical porous nanosheet array architecture, the NiSe@MoSe nanosheet arrays exhibit a high specific capacitance of 774 F g at the current density of 1 A g, which is almost 2 times higher than that (401 F g) of the NiSe matrix and about 7 times greater than that (113 F g) of the MoSe nanoparticles. Moreover, we report an asymmetric supercapacitor (ASC), which is fabricated by using the NiSe@MoSe nanosheet arrays as the positive electrode and the graphene nanosheets (GNS) as the negative electrode, with aqueous KOH as the electrolyte. The NiSe@MoSe//GNS ASC possesses an output voltage of 1.6 V, an energy density of 25.5 Wh kg at a power density of 420 W kg, and a cycling stability of 88% capacitance retention after 5000 cycles. These results indicate that the NiSe@MoSe nanosheet arrays are a good electrode for supercapacitors.