In situ synthesis of Fe2O3 nanosphere/Co3O4 nanowire-connected reduced graphene oxide hybrid networks for high-performance supercapacitors

Abstract

Three-dimensional (3D) hybrid networks consisting of reduced graphene oxide (rGO) sheets interconnected by Co₃O₄ nanowires (rGO/Co₃O₄), followed by the decoration of Fe₂O₃ nanospheres (NSs) (rGO/Co₃O₄@Fe₂O₃), were demonstrated by a facile hydrothermal method, with which the rGO/Co₃O₄ networks acted as nucleation sites for the in situ synthesis of Fe₂O₃ NSs. The intimate contacts between rGO, Co₃O₄ NWs and Fe₂O₃ NSs, which result in an excellent conductive behavior, provide a unique structure with huge potential for electrochemical property promoted electrochemical supercapacitors. The rGO/Co₃O₄@Fe₂O₃ hybrid networks as electrodes exhibit a high capacitance of 784 F g⁻¹ at 1 A g⁻¹ with 83% retention of the initial capacitance as the current density increases from 1 to 10 A g⁻¹, which is explained by the graphene-based interconnected structure owing to the advantages of accommodating the volume expansion between Co₃O₄ NWs and Fe₂O₃ NSs. The supercapacitor was assembled by applying a nickel aluminum layered double hydroxide (NiAl-LDH) structure and rGO/Co₃O₄@Fe₂O₃ as the electrode materials and yields an energy density of 70.78 W h kg⁻¹ at a power density of 0.29 kW kg⁻¹. The energy density can maintain 24.24 W h kg⁻¹ with 9.94 kW kg⁻¹.