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Ternary composite with immobilization of Fe2O3 nanoparticles (NPs) onto porous polydopamine-reduced graphene oxide framework, abbreviated as Fe2O3@PDA-RGO, was fabricated via a simple, scalable and cost-efficient hydrothermal reaction. The as-prepared 3D Fe2O3@PDA-RGO nanocomposite provides a specific surface area of 119.9 m2 g-1 on account of the well-dispersed Fe2O3 NPs (~35 nm) onto the PDA-RGO sheets as spacer. When applied as a special faradic electrode material in negative potential region, Fe2O3@PDA-RGO can offer 169 mA h g-1 (609 F g−1) at 1 A g-1. The fabricated AC//Fe2O3@PDA-RGO asymmetric supercapacitor (ASC) delivers an energy density of 35.8 W h kg-1 (0.94 mW h cm-3) at 800 W kg-1 (21 mW cm-3) and an outstanding cyclic stability (75.7% capacity retention after 10,000 cycles). The good performance of Fe2O3@PDA-RGO in single-electrode and ASC manifests the potential the ternary composite in energy storage devices. [ABSTRACT FROM AUTHOR]

Abstract High performances, cost-effectiveness, and facile preparation of electrode materials are of utmost importance for supercapacitors in practical applications. Herein, Ni(HCO 3) 2 nanoparticles (NPs) of low cost and environmental friendliness were embedded into polydopamine-reduced graphene oxide (PDA-RGO) networks via cost-effective hydrothermal route. It is shown the conducting PDA can uniformly distributes and robustly immobilizes Ni(HCO 3) 2 NPs in the nanocomposite while the ionic channels are improved for electrolyte access. Consequently, the as-prepared Ni(HCO 3) 2 -PDA-RGO composite offers the high Faradaic capacity of 870 C g−1 at 0.5 A g−1 and moderate rate capability. Furthermore, the assembled Ni(HCO 3) 2 -PDA-RGO//activated carbon hybrid supercapacitor (HSC) delivers a specific capacity of 192 C g−1 at 0.5 A g−1 within operation voltage window of 1.7 V. The maximum energy density of the HSC reaches to 45.3 Wh kg−1 at a power density of 425 W kg−1, and the initial specific capacity maintains 90.5% after 3000 successive charge-discharge cycles. The high energy density and good cycleability certify the potential of the ternary Ni(HCO 3) 2 -PDA-RGO composite in efficient and long lifetime energy storage systems. [ABSTRACT FROM AUTHOR]