Enhanced dielectric polarization loss of CoFe₂O₄/CeO₂ @ amorphous carbon sponge-structured nanocomposites enables high-performance electromagnetic wave absorption

The multi-interface structure plays a crucial role in facilitating the effectiveness of electromagnetic wave (EMW) absorption in nanomaterials. However, designing and fine-tuning such structure remain challenging due to the limited understanding of the relationship between structural characteristics and dielectric loss properties. Herein, we present a sponge-structured dual-core @ shell CoFe₂O₄/CeO₂@C nanocomposite featuring abundant heterojunctions and robust dielectric-magnetic coupling networks. This design aims to attain excellent impedance matching and significantly enhance EMW absorption performance of the nanocomposite. Specifically, CoFe₂O₄/CeO₂@C nanocomposite achieves an effective absorption bandwidth (EAB) of 6.13 GHz with a thickness of merely 2.2 mm. The exceptional EMW absorption performance can be attributed to the synergistic effect of multi-loss mechanisms, including interfacial polarization induced by the porous dual-core @ shell structure, oxygen vacancy defects arising from the intrinsic structural characteristics of CeO₂ and conductive loss brought by reversible migration of Co²⁺/Fe³⁺ and Ce³⁺/Ce⁴⁺. This study offers a robust strategy for the advancement of ferrite-based composites with enhanced dielectric properties and offers novel insights for the design of broadband EMW absorbing materials.