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

In this study, we report novel Ni0.85Se@MoSe2 nanosheet arrays prepared by a facile one-step hydrothermal method through nickel (Ni) foam as Ni precursor and the framework of MoSe2. Owing to the unique interconnection and hierarchical porous nanosheet array architecture, the Ni0.85Se@MoSe2 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 Ni0.85Se matrix and about 7 times greater than that (113 F g-1) of the MoSe2 nanoparticles. Moreover, we report an asymmetric supercapacitor (ASC), which is fabricated by using the Ni0.85Se@MoSe2 nanosheet arrays as the positive electrode and the graphene nanosheets (GNS) as the negative electrode, with aqueous KOH as the electrolyte. The Ni0.85Se@MoSe2//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 Ni0.85Se@MoSe2 nanosheet arrays are a good electrode for supercapacitors.