Growth of magnetic graphene films with higher electromagnetic interference shielding at moderate annealing temperatures.

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 °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 (~ 50 μm) provided a high EMI shielding effectiveness (SE) of ~ 52.76 dB in the X-band (8.2-12.4 GHz). This is found to be higher than that of bare graphene films (~ 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. [ABSTRACT FROM AUTHOR]