NiMoO4 nanosheets grown on MOF-derived leaf-like Co3O4 nanosheet arrays for high-performance supercapacitors

The hierarchical core-shell Co3O4@NiMoO4 nanosheet arrays on nickel foam are fabricated via a facile two-step method coupled with subsequent heat treatment. MOF-derived Co3O4 nanosheets as the core with considerable surface area offer easier paths for the ion/electron transport and more sites for the growth of NiMoO4. And the NiMoO4 nanosheets as the shell have a superior electrochemical activity and advantageous synergistic effect with Co3O4, which greatly improves the energy storage ability of the electrode. Benefiting from the unique structure and composition, the Co3O4@NiMoO4 electrode exhibits a superior specific areal capacitance of 2.3 F cm−2 at 1 mA cm−2 and a great rate capability (capacitance retention of 73% at 20 A cm−2), which is much better than that of bare Co3O4 (0.1 F cm−2) and NiMoO4 (0.49 F cm−2). Additionally, the as-assembled Co3O4@NiMoO4//AC asymmetric supercapacitor exhibits an excellent energy density of 0.249 mWh cm−2 at a power density of 1.6 mW cm−2 and outstanding cycling stability of 80.7% retention at 10 mA cm−2 after 4000 cycles. These remarkable electrochemical properties indicate that the as-prepared hierarchical Co3O4@NiMoO4 nanosheet arrays have potential application prospect in high-performance supercapacitors.