Adsorption of graphene on an Fe3O4 surface: A molecular dynamics simulation study

A molecular dynamics (MD) simulation was used to investigate the adsorption of graphene oxide (GO) and graphene (G) onto an Fe₃O₄(111) surface. The MD simulation results indicated that the direction of the GO/G sheets introduced onto the Fe₃O₄(111) surface affected the morphologies of the GO/G sheets and the interface interaction energies. When the GO/G sheets were introduced onto the Fe₃O₄(111) surface from the parallel direction, a smooth, single-layered structure of the GO/G sheets formed, and the interface interaction energies were low. The interface interaction energy of GO-Fe₃O₄ interface was lower than that between G and Fe₃O₄(111) surfaces because of the strong interactions between the carboxyl groups on the GO edges and the iron atoms on the surface. The ideal distribution and lower interface interaction energies of the polymers (PEG and PEI) with GO/G indicated that the GO/G coated layer on the Fe₃O₄ surface could be further modified. According to results, GO, under specific stirring speeds, was adsorbed onto the Fe₃O₄ surface along the parallel direction and formed stable graphene-Fe₃O₄ composite microspheres suitable for drug carrier applications. Both GO and G covered the rough, grooved surface of Fe₃O₄(111), and the adsorption of GO was faster than that of G.