Hollow Fe3O4 microspheres/graphene composites with adjustable electromagnetic absorption properties

Abstract

Fe3O4@rGO composites, consisting of monodisperse hollow Fe3O4 microspheres with an average particle size of 320 nm and reduced graphene oxide, were prepared by using a facile and efficient two-step solvothermal method. Compositions, microstructure and electromagnetic properties of the Fe3O4@rGO composites were systematically studied by using various analytical techniques. Compared with the hollow Fe3O4 and bare rGO, the Fe3O4@rGO composites have significantly higher electromagnetic absorption performances. A maximum reflection loss (RL) of −49.8 dB was achieved at 8.48 GHz, with a wide bandwidth of 3.3 GHz from 6.6 GHz to 9.9 GHz, when the Fe3O4@rGO composites with a Fe3O4 to rGO mass ratio of 2:1 were synthesized at 200 °C for 7 h by using ethylene glycol as the hydrothermal solvent. The absorption covered the mid-low frequency X-band, while the optimum match thickness was 3.0 mm. The peak position of the minimum reflectance of the Fe3O4@rGO composites shifted to lower frequencies with increasing content of Fe3O4. The electromagnetic absorption properties of the Fe3O4@rGO composites could be adjusted by controlling the mass ratio of the two components, reaction time and the sample thickness. SuchhHollow Fe3O4 microspheres/graphene composites could be used as light-weight microwave absorption materials at the mid-low frequency bands.