Core-shell CoFe₂O₄@C nanoparticles coupled with rGO for strong wideband microwave absorption

Strong absorption and large bandwidth are two contributors to materials’ absorbing performance. In this work, a series of multi-element core-shell magnetic nano-particle composite layered graphene absorbing materials CoFe₂O₄@C/rGO (CCr) were prepared by adjusting carbon shell thickness. The CCr at a low thickness achieved strong microwave absorption and a wide effective absorption bandwidth. Not only the core-shell structure of the magnetic nanoparticle CoFe₂O₄@C (CFO@C) increases the interface loss, but both the coating carbon shell and the core CoFe₂O₄ (CFO) are beneficial to improve impedance matching. Due to the synergistic effect of the dielectric and magnetic properties of graphene and ferrite, CCr possessed high absorption performance, and its minimum reflection loss reached (R_Lmin) −52.5 dB when the thickness was only 2 mm. At the same time, the effective absorption bandwidth (EAB) was 5.68 GHz when the thickness was only 1.7 mm. The chemically stable core-shell dielectric nanocomposite provided a new solution for preparing materials with excellent chemical structure and high absorbing properties.