Mn-doping has great influence on the structural and electrical properties of NiMoO 4 , which plays an important role in determining its electrochemical activities. In this work, Mn-doped NiMoO 4 was prepared. Structural characterization and theoretical calculation reveal that Mn-doped NiMoO 4 (Mn 0.1 Ni 0.9 MoO 4 ) has smaller unit cell parameters and is more reactive than NiMoO 4 because of the defects produced by Mn-doping. On the basis of that, we prepared a composite consisting of Mn 0.1 Ni 0.9 MoO 4 mesoporous nanorods and reduced graphene oxide (Mn 0.1 Ni 0.9 MoO 4 /rGO), which was assembled into a symmetrical all-solidstate device as electrode material, with alkaline poly(vinyl alcohol) as solid-state electrolyte. The device shows a good specific capacitance of 109.3 F•g −1 at 1 A•g −1 in a rather wide voltage range of 0−1.8 V, exhibits an excellent cycling stability with 96.1% of the capacitance retained after 200 cycles, and delivers a high energy density of 49.2 Wh•kg −1 at 1800 W•kg −1 . The all-solid-state supercapacitor owns superior flexibility and maintains 83.6% of its initial specific capacitance under the bent condition. When tested in a three-electrode system, the Mn 0.1 Ni 0.9 MoO 4 /rGO composite exhibits a maximum specific capacitance of 688.9 F•g −1 at 0.5 A•g −1 that is much better than NiMoO 4 and Mn 0.1 Ni 0.9 MoO 4 . The results show that the Mn 0.1 Ni 0.9 MoO 4 /rGO composite stands out as a kind of transition-metal-doped electrode material for flexible all-solid-state supercapacitors.

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Nickel phosphate (Ni(PO)) is a promising electrode material for electrochemical capacitors, but the low intrinsic electrical conductivity and poor rate capability of Ni(PO) are the main challenges. To tackle these problems, amorphous mesoporous Ni(PO) with a pore diameter of 2-10 nm is grown on reduced graphene oxide (rGO), and a Ni(PO)/rGO composite is obtained via a facile hydrothermal-calcination method in this work. The Ni(PO)/rGO composite calcined at 300 °C (Ni(PO)/rGO-300) possesses a uniform particle size and a high specific surface area of 198.72 m g. Benefiting from the structural characteristics, the synergistic effect of components and the high specific surface area, the Ni(PO)/rGO-300 composite exhibits an extremely high specific capacitance of 1726 F g at 0.5 A g and an excellent rate capability of 850 F g at 25 A g. In addition, the assembled Ni(PO)/rGO-300//activated carbon asymmetric electrochemical capacitor delivers a good energy density of 57.42 W h kg at a power density of 160 W kg. Compared with Ni(PO)/rGO composites calcined at other temperatures and other nickel-phosphorus compounds reported in the literature, the Ni(PO)/rGO-300 composite containing amorphous mesoporous Ni(PO) exhibits superior electrochemical performance, representing a new kind of electrode material for electrochemical capacitors.

Graphene based copper‐nickel bimetal nanocomposite (Cu3Ni2‐rGO) was prepared via a one‐step solvothermal procedure, in which Ni(OH)2 and Cu(OH)2 were used as precursors. Structural characterization confirms that the as‐prepared Cu3Ni2‐rGO nanocomposite is composed of Cu3Ni2 nanoparticles in the size range of 20–100 nm and the reduced graphene oxide (rGO) sheets. Benefiting from the combination of Cu3Ni2 and rGO, the Cu3Ni2‐rGO nanocomposite exhibits excellent catalytic performance on reducing highly toxic Cr(VI) at room temperature. The reduction of Cr(VI) (40 mL, 100 mg L−1) can be completed within 6 min using Cu3Ni2‐rGO nanocomposite as the catalyst, which is much more efficient than using monometallic nanocomposite containing only Cu or Ni. Moreover, Cu3Ni2‐rGO nanocomposite can be magnetically separated, which enables effective recycle. Besides, Cu3Ni2‐rGO shows good cycling stability.