Microwave assisted synthesis of MnO2 on nickel foam-graphene for electrochemical capacitor

Highlights: •Three-dimensional synthesis of graphene using CVD. •Hydrothermal deposition (microwave irradiation) of MnO2 on graphene. •Morphologies of the composite reveals flower-like nanostructures of MnO2 on graphene. •Composite exhibit excellent electrochemical performance. -- Abstract: A green chemistry approach (hydrothermal microwave irradiation) has been used to deposit manganese oxide on nickel foam-graphene. The 3D graphene was synthesized using nickel foam template by chemical vapor deposition (CVD) technique. Raman spectroscopy, X-ray diffraction (XRD), scanning electron and transmission electron microscopies (SEM and TEM) have been used to characterize structure and surface morphology of the composite, respectively. The Raman spectroscopy measurements on the samples reveal that 3D graphene consists of mostly few layers with low defect density. The composite was tested in a three electrode configuration for electrochemical capacitor, and exhibited a specific capacitance of 305 F g−1 at a current density of 1 A g−1 and showed excellent cycling stability. The obtained results demonstrate that microwave irradiation technique could be a promising approach to synthesis graphene based functional materials for electrochemical applications