A novel synthesis of size-controllable mesoporous NiMoO4 nanospheres for supercapacitor applications

A novel hydrothermal emulsion method is proposed to synthesize mesoporous NiMoO4 nanosphere electrode material. The size of sphere-shaped NiMoO4 nanostructure is controlled by the mass ratio of water and oil phases. Nickel acetate tetrahydrate and ammonium heptamolybdate were used as nickel and molybdate precursors, respectively. The resultant mesoporous NiMoO4 nanospheres were characterized by X-ray diffraction, N2 adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. The electrochemical performances were evaluated by cyclic voltammetry (CV), cyclic chronopotentiometry (CP), and electrochemical impedance spectroscopy (EIS) in 6 M KOH solution. The typical mesoporous NiMoO4 nanospheres exhibit the large specific surface area of 113 m2 g−1 and high specific capacitance of 1443 F g−1 at 1 A g−1, an outstanding cyclic stability with a capacitance retention of 90 % after 3000 cycles of charge-discharge at a current density of 10 A g−1, and a low resistance.