Ni0.85Se@MoSe₂ Nanosheet Arrays as the Electrode for High-Performance Supercapacitors

In this study, we report novel Ni 0.85 Se@MoSe 2 nanosheet arrays prepared by a facile one-step hydrothermal method through nickel (Ni) foam as Ni precursor and the framework of MoSe 2 . Owing to the unique interconnection and hierarchical porous nanosheet array architecture, the Ni 0.85 Se@MoSe 2 nanosheet arrays exhibit a high specific capacitance of 774 F g –1 at the current density of 1 A g –1, which is almost 2 times higher than that (401 F g –1 ) of the Ni 0.85 Se matrix and about 7 times greater than that (113 F g –1 ) of the MoSe 2 nanoparticles. Moreover, we report an asymmetric supercapacitor (ASC), which is fabricated by using the Ni 0.85 Se@MoSe 2 nanosheet arrays as the positive electrode and the graphene nanosheets (GNS) as the negative electrode, with aqueous KOH as the electrolyte. The Ni 0.85 Se@MoSe 2 //GNS ASC possesses an output voltage of 1.6 V, an energy density of 25.5 Wh kg –1 at a power density of 420 W kg –1, and a cycling stability of 88% capacitance retention after 5000 cycles. These results indicate that the Ni 0.85 Se@MoSe 2 nanosheet arrays are a good electrode for supercapacitors.