Freestanding three-dimensional reduced graphene oxide/MnO₂ on porous carbon/nickel foam as a designed hierarchical multihole supercapacitor electrode

The optimization of the electrodes structure is crucial for supercapacitors. Herein, we report a novel three-dimensional (3D) hierarchical multihole architecture of ternary reduced graphene oxide (rGO)/MnO₂/carbon foam (CF) nanocomposites. Thereinto, CF not only firstly serves as conductive skeleton but also offers primary pore structure with nickel foam and supporter for electrochemical deposition (ECD) of MnO₂. Furthermore, rGO covered on electrodes surface both prevents the exfoliation of MnO₂ and integrates with it to construct secondary pore structure. The configuration with three components synergistic effects leads to a high specific capacitance of 356.5 F g⁻¹ at a scan rate of 10 mV s⁻¹ and a long cycle life along with 93.6% specific capacitance retained after 2000 cycles. Also, it even remained 30.6 Wh kg⁻¹ at a large power density of 13.5 kW kg⁻¹.