Hierarchical structures composed of MnCo₂O₄@MnO₂ core–shell nanowire arrays with enhanced supercapacitor properties

In this paper, hierarchical MnCo2O4@MnO2 core-shell nanowire arrays (MnCo2O4@MnO2 NWAs) with mesoporous and large surface area are synthesized on 3D nickel foam via a facile, two-step hydrothermal approach without any adscititious surfactant and binder. The electrode architecture takes advantage of the synergistic effects contributed from both the porous MnCo2O4 nanowire core and the MnO2 shell layer. The fabricated MnCo2O4@MnO2 NWA electrode for supercapacitors in aqueous electrolyte exhibits a significantly enhanced specific capacitance (858 F g(-1) at 1 A g(-1)), high energy density (36.0 Wh kg(-1) at 252 W kg(-1)) and long-life cycling stability (retaining 88% of the initial capacitance after 5000 cycles). Then, a symmetrical supercapacitor is fabricated by assembling two MnCo2O4@MnO2 NWA-based electrodes, which shows a high specific capacitance of 678 F g(-1) at 1 A g(-1) and a high energy density of 135.6 Wh kg(-1) at 513 W kg(-1). Thereby, the hierarchical core-shell MnCo2O4@MnO2 NWAs are very promising as next generation high-performance long-life cycling supercapacitors.