Comparison of the electrochemical performance of NiMoO4 nanorods and hierarchical nanospheres for supercapacitor applications.

Much attention has been paid to exploring electrode materials with enhanced supercapacitor performance as well as relatively low cost and environmental friendliness. In this work, NiMoO4 nanospheres and nanorods were synthesized by facile hydrothermal methods. The hierarchical NiMoO4 nanospheres were about 2.5 μm in diameter and assembled from thin mesoporous nanosheets with a thickness of about 10-20 nm. The NiMoO4 nanorods were about 80 nm in diameter and about 300 nm to 1 μm in length. Their electrochemical properties were investigated for use as electrode materials for supercapacitors (SCs). The NiMoO4 nanospheres exhibited a higher specific capacitance and better cycling stability and rate capability, which were attributed to their large surface area and high electrical conductivity. The specific capacitances were 974.4, 920.8, 875.5, 859.1, and 821.4 F/g at current densities of 1, 2, 4, 6, and 10 A/g, respectively. Remarkably, the energy density was able to reach 20.1 Wh/kg at a power density of 2100 W/kg. After 2000 cycles, the NiMoO4 nanospheres still displayed a high specific capacitance of about 631.8 F/g at a current density of 5 A/g. These results implied that the hierarchical NiMoO4 nanospheres could be a promising candidate for use as high-performance SCs.