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A three-dimensional reduced graphene oxide/nickel-cobalt sulfide (RGO/NiCo2S4) aerogel was fabricated by an efficient and facile one-step hydrothermal approach. The NiCo2S4 needle-like structure consisted of many small nanoparticles well attached to the surface of the RGO sheet. The prepared aerogel had high porosity and conductivity. As an active electrode material for supercapacitors, the RGO/NiCo2S4 aerogel exhibited a large capacitance of 813 F g−1 at 1.5 A g−1. Besides, the asymmetric supercapacitor (RGO/NiCo2S4 aerogel//RGO) showed a Cs of 45.3 F g−1 at 1.0 A g−1 and a suitable remaining capacitance of over 84.3 % after 2000 cycles. The asymmetric supercapacitor had a high energy density of 40.3 Wh kg−1 at 375.0 W kg−1 and a power density of 26.2 kW kg−1 at 3.7 kWh kg−1, which suggests this device has great potential applications in energy storage.

A binder-free 3D electrode of MnO 2 arrays on graphene@nickel foam was successfully prepared via a two-step method. The nickel foam was first coated with a graphene sheet by chemical vapor deposition (CVD) and then decorated with MnO 2 of different morphologies, ultrathin MnO 2 nanosheets and ultralong MnO 2 nanowires, by facile hydrothermal method. Due to the large specific surface area, high electronic conductivity and good capacitance of electrode materials, the obtained electrode exhibited rapid electron and ion transport, large electroactive surface area, and excellent structural stability. The electrode showed a high specific capacitance of 723 F cm −2 at a high current density of 30 mA cm −2 and a good cycling stability (with a negligible 2.4% decay in specific capacitances after 2300 cycles), promising its applications to high-performance supercapacitors.

Three-dimensional polyaniline grafted reduced graphene oxide (3D RGO-g-PANI) composite was prepared by an efficient two-step method. Firstly, graphene oxide sheets were grafted with PANI chains, forming graphene oxide grafted PANI composites. Secondly, RGO-g-PANI aerogels were obtained from GO-g-PANI composites by hydrothermal and drying processes. The 3D RGO-g-PANI aerogel composite was used as active materials to coat the glassy carbon electrodes for checking the electrochemical properties for supercapacitor application. The obtained specific capacitance was 1600 F g−1 at a very high current density of 12 A g−1 and an excellent cycle stability (91.3% capacitance retention after 3000 cycles), suggesting its potential application for a high performance supercapacitors.