Hybrids of nickel manganate nanosheets and nanoflowers on reduced graphene oxide for supercapacitors

Nickel manganate/reduced graphene oxide (NiMn2O4/rGO) composites were synthesized by a hydrothermal method. The morphology, specific surface area and capacitance performance were influenced by the type of solvent. The NiMn2O4/rGO synthesized with deionized water as solvent has nanosheets structure, the specific capacitance of NiMn2O4/rGO nanosheets is 1360 F g(-1) at 1 A g(-1). The NiMn2O4/rGO synthesized with anhydrous ethanol as solvent has a nanoflower structure, the specific capacitance of NiMn2O4/rGO nanoflowers is 1692 F g(-1) at 1 A g(-1). After 5000 cycles, the specific capacitance retention rate of NiMn2O4/rGO nanoflowers is 81% at 5 A g(-1), that of NiMn2O4/rGO nanosheets is 90%. NiMn2O4/rGO nanoflowers prepared with ethanol as solvent shows superior specific capacitance; NiMn2O4/rGO nanosheets prepared with deionized water as solvent has good rate performance and cycling stability. (C) 2020 Elsevier B.V. All rights reserved.