Electrodeposition of hierarchical manganese oxide on metal nanoparticles decorated nanoporous gold with enhanced supercapacitor performance

Highlights: • Pt-NPs decorated NPG as current collector for electrodeposition of MnO_x nanosheets. • Pt-NPs facilitate the formation of MnO_x nanosheets and improve the conductivity. • MnO_x/Pt@NPG electrode shows low contact resistance and excellent cycling stability. • Nanosized subunits in hybrid electrode can improve the electrochemical performance. - Abstract: A novel three dimensional nanoarchitecture of manganese oxide nanosheets/Pt@nanoporous gold (MnO_x/Pt@NPG) was designed and synthesized by galvanostatic electrodepositon for supercapacitors application. Nanoporous gold (NPG) membrane was fabricated by a dealloying method as a current collector and discontinuous platinum nanoparticles were pulse electrodeposited on NPG. The morphology and chemical composition of the MnO_x/Pt@NPG products were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the as-prepared MnO_x as an electrode material for supercapacitor were investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy measurements in 1 M Na₂SO₄ electrolyte. Importantly, the optimized MnO_x/Pt@NPG hybrid electrodes obtain a maximum specific capacitance of 775 F g⁻¹ at 1 A g⁻¹ (about two times larger than that of MnO_x/NPG electrodes with 404 F g⁻¹), about half of the internal resistance of MnO_x/NPG electrodes and excellent cycling stability, making it a promising candidate for supercapacitors