Reduced graphene oxide modified mesoporous FeNi alloy/carbon microspheres for enhanced broadband electromagnetic wave absorbers

Absorbers have been investigated widely so as to eliminate or at least significantly attenuate the hazards of electromagnetic radiation. A porous structure is believed to be beneficial for the high-performance of microwave absorption. Here, an embedded magnetic mesoporous composite (FeNi alloyed porous carbon microspheres, FeNi/CS) is for the first time evaluated as a microwave absorbing material. Upon combining reduced graphene oxide (rGO) with the FeNi/CS composite, a multiple-component absorber of FeNi/CS/rGO is synthesized via hydrothermal and freeze-drying processes. Compared to unmodified FeNi/CS, the FeNi/CS/rGO composite provides an effective component and a more specific structure, which is favorable for translating microwave into thermal energy or other forms of energy. The minimum reflection loss (RL) value of the FeNi/CS/rGO composite reaches -45.2 dB at a thickness of 1.5 mm, and the maximum effective microwave absorption bandwidth (RL < -10 dB) is up to 5.0 GHz at d = 1.5 mm. In virtue of the dielectric loss, magnetic loss, unique heterostructure of the absorber, and impedance matching, the FeNi/CS/rGO composite exhibits overwhelming advantages of low density, small thickness, broad bandwidth, strong absorption and high anti-oxidation capability.