Layer-by-layer assembly of manganese–cobalt–nickel oxide nanosheets/graphene composite films

• Manganese–cobalt–nickel oxide nanosheets/graphene composite films.
• Assembling behavior between FRGO and MnCoNiO2 nanosheets.
• A synergistic effect exists between FRGO and MnCoNiO2 nanosheets.
• MnCoNiO2–FRGO electrode shows good electrochemical stability at high scan rates.

Two different nanosheets, poly(diallyldimethylammonium chloride)-functionalized graphene nanosheets (FRGO) and manganese–cobalt–nickel oxide nanosheets (MnCoNiO2) are used as building blocks for the assembly of manganese–cobalt–nickel oxide nanosheets/graphene composite films (MnCoNiO2–FRGO). Sequential adsorption of these oppositely-charged nanosheets yields multilayer films, whereas simple mixing produces a lamellar flocculate. UV–visible spectra exhibit a progressive increase of absorbance with increasing number of deposition cycles, providing strong evidence for the regular growth of multilayer films. The combination of FRGO and MnCoNiO2 nanosheets produces a new layered structure with a planar spacing of 2.36 nm, which is in agreement with the sum of the thicknesses of MnCoNiO2 and FRGO nanosheets. The MnCoNiO2–FRGO composite films show a higher specific capacitance and good electrochemical stability because of a synergistic effect existed between the FRGO nanosheets and MnCoNiO2 nanosheets.

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