NiMoO4-modified MnO2 hybrid nanostructures on nickel foam: electrochemical performance and supercapacitor applications

A novel self-supported electrode of NiMoO4-modified MnO2 hybrid nanostructures on nickel foam has been designed and synthesized using a combination of hydrothermal syntheses. Based on the morphology, a possible mechanism that the surface modification of NiMoO4 not only prevents the MnO2 from dissolving in an alkaline electrolyte of KOH but also improves the capacity is proposed. Therefore, this electrode manifests a satisfying capacitance of 2525 F g(-1) (within a potential range of -0.2-0.6 V at a current density of 0.5 A g(-1)), outstanding rate capability and excellent cycling stability. The reason that the hybrid NiMoO4-modified MnO2 electrode has excellent comprehensive performance is not only the coupling effect which between NiMoO4 and MnO2 but also the semiconductor surface recombination effect which improved the electrical conductivity. Moreover, an asymmetric supercapacitor has been assembled, where the hybrid NiMoO4-modified MnO2 and activated carbon act as the positive and negative electrodes, respectively, and a maximum specific capacitance of 135 F g(-1) is demonstrated within a cell voltage between 0 and 1.6 V at a current density of 0.5 A g(-1); thus, the supercapacitor exhibits a high energy density and stable power characteristics.