Hierarchical MnCo₂O₄@NiMoO₄ as free-standing core-shell nanowire arrays with synergistic effect for enhanced supercapacitor performance

The unique synergistic effect of hierarchical core-shell structures demonstrates great potential for designing the next-generation electrode materials for supercapacitors. In this work, we design binder-free MnCo₂O₄@NiMoO₄ heterostructure core-shell nanowire arrays (NWAs) grown over a current collector of nickel foam (NF) achieved through a modified and simple hydrothermal process. The capacitive performance of the core MnCo₂O₄ NWAs was remarkably improved by growing a layer of NiMoO₄ nanosheets (1244 F g^-1 at 1 A g^-1), which is superior to the capacitance of pristine MnCo₂O₄ (457.85 F g^-1 at 1 A g^-1). Moreover, the prepared MnCo₂O₄@NiMoO₄ core-shell NWAs have been used along with commercial activated carbon (AC) to fabricate an asymmetric full supercapacitor device. MnCo₂O₄@NiMoO₄//AC delivers a high energy density (42 W h kg^-1) at a power density of 852.3 W kg^-1 and a good cyclability with 93% of the initial capacitance retained at the end of 8000 successive charge/discharge cycles. Therefore, the MnCo₂O₄@NiMoO₄ electrode material holds a great promise as a suitable candidate for high performance supercapacitors.