In-Situ Grown NiMnO/GO Nanocomposite Material on Nickel Foam Surface by Microwave-Assisted Hydrothermal Method and Used as Supercapacitor Electrode.

The NiMnO/graphene oxide (GO) nanocomposite material was in situ grown on the surface of a nickel foam 3D skeleton by combining the solvent method with the microwave-assisted hydrothermal method and annealing; then, its performance was investigated as a superior supercapacitor electrode material. When nickel foam was soaked in GO aqueous or treated in nickel ion and manganese ion solution by the microwave-assisted hydrothermal method and annealing, gauze GO film or flower-spherical NiMnO was formed on the nickel foam surface. If the two processes were combined in a different order, the final products on the nickel surface had a remarkably different morphology and phase structure. When GO film was first formed, the final products on the nickel surface were the composite of NiO and MnO, while NiMnO/GO nanocomposite material can be obtained if NiMnO was first formed (immersed in 2.5 mg/L GO solution). In a 6M KOH solution, the specific capacitance of the latter reached 700 F/g at 1 A/g which was superior to that of the former (only 35 F/g). However, the latter's specific capacitance was still inferior to that of in-situ grown NiMnO on nickel foam (802 F/g). Though the gauze-formed GO film, almost covering the preformed flower-spherical NiMnO, can also contribute a certain specific capacitance, it also restricted the electrolyte diffusion and contact with NiMnO, accounting for the performance decrease of the NiMnO/GO nanocomposite. A convenient method was raised to fabricate the nanocomposite of carbon and double metal oxides.