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

Abstract 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–MnO 2 ) is prepared by hydrothermally treating an isopropyl alcohol suspension of HRGO, MnCl 2 ·4H 2 O, and KMnO 4 at 90 °C for 1 h. α–MnO 2 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–MnO 2 hybrid material. The self–assembly between HRGO nanosheets and α–MnO 2 particles can increase the specific surface area of the prepared material (about 196 m 2  g −1 ). The HRGO nanosheets improve the utilization efficiency of α–MnO 2 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 Na 2 SO 4 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.