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

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. (C) 2015 Elsevier Ltd. All rights reserved.