Design and synthesis of Au nanoparticles decorated NiCo₂O₄@MnO₂ core-shell nanowires for high-performance supercapacitors

We developed a facile synthetic method to construct a novel sandwiched coaxial core–shell heterojunction electrode by combining MnO₂ nanoflakes wrapped in Au nanoparticles decorated NiCo₂O₄ nanowires (NW) with carbon fiber cloth (NiCo₂O₄@Au@MnO₂). XRD, SEM and TEM techniques were used to characterize the structures of NiCo₂O₄@Au@MnO₂. Electrochemical measurements confirmed that such nanostructured composites possessed an electrochemical capacitance that was higher than that of each individual component due to synergistic effects. The NiCo₂O₄@Au@MnO₂ electrode has extremely high specific capacitance (1906.6 F g⁻¹ at 1 A g⁻¹) and excellent cycling stability (92.5% after 10,000 cycles) in a three-electrode system with 6M KOH electrolyte. Furthermore, the performance of an asymmetric supercapacitor of NiCo₂O₄@Au@MnO₂//AC was further evaluated, and the energy density was 98.3 Wh kg⁻¹ at a power density of 0.8 W kg⁻¹. The excellent electrochemical performance of such nanoscale architecture electrodes provides a new route for developing high-performance supercapacitors with 3D multicomponent heterojunction core-shell structures.