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

Abstract

Graphene was introduced onto an embedded magnetic mesoporous composite. The overall microwave absorption performance of the material was significantly improved.

Abstract

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.