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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