The attachment of Fe3O4 nanoparticles to graphene oxide by covalent bonding

Hybrids of graphene oxide (GO) nanosheets and surface-modified Fe3O4 nanoparticles (NPs) were fabricated by a two-step process. First, Fe3O4 was modified by tetraethyl orthosilicate and (3-aminopropyl) triethoxysilane to introduce amino groups on its surface. Second, the amino groups of Fe3O4 were reacted with the carboxylic groups of GO with the aid of 1-ethyl-3-(3-dimethyaminopropyl)carbodiimide and N-hydroxysuccinnimide to form a GO–Fe3O4 hybrid. The attachment of Fe3O4 NPs on the GO nanosheet surface was confirmed by transmission electron microscopy and Fourier-transform infrared spectroscopy. The adsorption capacity of GO–Fe3O4 for methylene blue and neutral red cationic dyes was as high as 190.14 and 140.79 mg/g, respectively. The GO–Fe3O4 hybrids could be reduced to form graphene–Fe3O4 hybrids by using NaBH4 as reducing agent and be used to prepare magnetic GO films.