High performance graphene/manganese oxide hybrid electrode with flexible holey structure

•Graphene/manganese oxide hybrid nanocomposite with holey structure was prepared.•α–MnO2 with needle–like morphology was uniformly dispersed on the surface of HRGO.•The holey structure provided a high density of porosity to improve ions transport.•HRGO/α–MnO2 hybrid electrode exhibited a high specific capacitance of 348 F g−1.

Graphene with flexible holey structure (HRGO) is firstly prepared by a wet chemical method in mild acid oxidation, and then graphene/manganese oxide hybrid nanocomposite with holey structure (HRGO/α–MnO2) is prepared by hydrothermally treating an isopropyl alcohol suspension of HRGO, MnCl2·4H2O, and KMnO4 at 90 °C for 1 h. α–MnO2 with needle–like morphology is uniformly dispersed on the surface of HRGO nanosheets, which prevents the restacking of the graphene nanosheets and allows graphene nanosheets to exist in a complete exfoliation state in HRGO/α–MnO2 hybrid material. The self–assembly between HRGO nanosheets and α–MnO2 particles can increase the specific surface area of the prepared material (about 196 m2 g−1). The HRGO nanosheets improve the utilization efficiency of α–MnO2 in the hybrid electrode, while the holey structure provides a high density of porosity to facilitate charges and ions transport. The prepared electrode material exhibits a high specific capacitance of 348 F g−1 at 5 mV s−1 in 1 mol L−1 Na2SO4 electrolyte with a capacitance retention of 86% after 1000 cycles at a constant current density of 10 A g−1. This preparation method may open new opportunity for preparing other types of graphene–based hybrid materials for technological applications.

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