The microwave absorption, electromagnetic interference shielding, and microwave response mechanism of graphene hybrids are highlighted, including relaxation, charge transport, magnetic resonance,etc.

Lightweight and high-efficiency microwave absorption materials with tunable electromagnetic properties is a highly sought-after goal and a great challenge for researchers. In this work, a simple strategy of confinedly implanting small NiFe 2 O 4 clusters on reduced graphene oxide is demonstrated, wherein the magnetic clusters are tailored, and more significantly, the electromagnetic properties are highly tuned. The microwave absorption was efficiently optimized yielding a maximum reflection loss of-58 dB and ~ 12 times broadening of the bandwidth (at-10 dB). Furthermore, tailoring of the implanted magnetic clusters successfully realized the selective-frequency microwave absorption, and the absorption peak could shift from 4.6 to 16 GHz covering 72% of the measured frequency range. The fascinating performances eventuate from the appropriately tailored clusters, which provide optimal synergistic effects of the dielectric and magnetic loss caused by multi-relaxation, conductance, and resonances. These findings open new avenues for designing microwave absorption materials in future, and the well-tailored NiFe 2 O 4-rGO can be readily applied as a multi-functional microwave absorption material in various fields ranging from civil and commerce to military and aerospace.

High efficiency and light weight are key factors for microwave absorption materials.Searching for the above necessary features is still a great challenge. Herein, we decorated the small magnetic nickel ferrite nanoparticles on the reduced graphene oxides nanosheets uniformly (NiFe2O4/r-GO) via a facile one-pot hydrothermal method with free chemical reducing agents, and investigated its permittivity, permeability and microwave absorption.Notably, we find an effective strategy of tuning microwave attenuation by the synergistic effect of dielectric and magnetic loss, which originates from inducing multiple relaxations and multiple resonances. The best impedance matching of NiFe2O4/r-GO was sought out. The minimum reflection loss (RL) can reach -42 dB with a broad bandwidth (RL ≤ -10 dB) of 5.3GHz. Meanwhile, the multiple regions endow absorbers with selectivity for efficient absorption. Our results demonstrate that the as-prepared NiFe2O4/r-GO is a promising candidate for application in communication device, high speed processors, information security, electronic countermeasures and electromagnetic interference shielding.Recently, inducing magnetic materials on the r-GO has been considered as an effective way to further develop EM attenuation performances for combining the advantages of r-GO and magnetic components. 14-19 Magnetic materials are continually reported to reveal superior microwave attenuation capacity, such as magnetic metals, magnetic oxides, ferrites and ferroelectric. 20-26 Among them, soft magnet nickel ferrite with spinel structure have extensive 11 and mass ratio. Notably, we find an effective strategy of tuning microwave attenuation by the synergistic effect of dielectric and magnetic loss, which originates from inducing multiple relaxations and multiple resonances. All these results demonstrate that the NiFe2O4/r-GO is a superior candidate for efficient and tunable multi-region microwave absorbers, providing a promising prospect to design outstanding microwave absorbers.

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