Confinedly implanted NiFe2O4-rGO: Cluster tailoring and highly tunable electromagnetic properties for selective-frequency microwave absorption

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 NiFe2O4 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 similar to 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 NiFe2O4-rGO can be readily applied as a multi-functional microwave absorption material in various fields ranging from civil and commerce to military and aerospace.