▎ 摘　　要

Ultrathin, highly conductive, and free-standing graphene films have been seen as promising electromagnetic interference (EMI) shielding materials for portable electronic devices. However, they are still expensive. In this paper, a magnetic graphene film decorated with Fe3O4 nanoparticles was prepared through in situ wet chemical synthesis followed by catalytic graphitization. A graphitic structure was obtained at a moderate annealing temperature (1000 degrees C), after introducing Fe3O4 nanoparticles. This temperature is much lower than the conventional graphitization temperature, which reduces the synthesis costs of graphene film. In addition, Fe3O4 also behaved as microwave absorbers, enhancing the EMI shielding performances. The resulting ultrathin film ( similar to 50 mu m) provided a high EMI shielding effectiveness (SE) of similar to 52.76 dB in the X-band (8.2-12.4 GHz). This is found to be higher than that of bare graphene films ( similar to 33.45 dB) prepared under the same temperature and sufficient to screen about 99.999% of microwave radiation. Furthermore, absorption was the dominant shielding mechanism for the prepared film owing to the contribution of Fe3O4 nanoparticles that reduced the electromagnetic pollution resulting from secondary reflections. The catalytic graphitization strategy could provide a low-cost approach for fabricating efficient graphene-based EMI shielding materials for portable electronic device applications.