Hierarchical heterostructures of Ag nanoparticles decorated MnO2 nanowires as promising electrodes for supercapacitors†
Coating the redox-active transition-metal oxides (e.g., MnO2) with a conductive metal layer is one efficient approach to improve the electrical conductivity of the oxide-based electrodes, which could largely boost the energy density and power density of supercapacitors. Here, we report a facile yet efficient method to uniformly decorate conductive silver (Ag) nanoparticles (∼10 nm) on MnO2 nanowires (width of ∼10–20 nm), which leads to a remarkable improvement of the electrical conductivity and the supercapacitive performance of MnO2-based electrodes. For instance, at a low scan rate of 10 mV s−1, the as-designed Ag/MnO2 hybrid electrode delivers a specific capacitance of 293 F g−1, which is twofold higher than that of the bare MnO2 electrode (∼130 F g−1). In addition, the highly conductive Ag nanoparticle layer can also improve the rate capability of the Ag/MnO2 nanowire electrode, delivering a high specific energy density and power density of 17.8 W h kg−1 and 5000 W kg−1, respectively, at a current density of 10 A g−1.