Boosting dual-interfacial polarization by decorating hydrophobic graphene with high-crystalline core-shell FeCo@Fe3O4 nanoparticle for improved microwave absorption

Manufacturing heterostructure architectures with multiple interfaces and understanding the interfacial polarizations are important for exploring high-efficient microwave absorbents. Herein, high-crystalline core-shell FeCo@Fe3O4 nanoparticles were in-situ anchored on graphene. The FeCo@Fe3O4/graphene hybrids reveal boosting microwave absorption which can be adjusted by controlling the graphene component. The hybrids show an optimal reflection loss of -74.4 dB at 9.6 GHz with a thickness of 2.58 mm. The effective absorption bandwidth can reach 3.7-18 GHz when the thickness is 1.5-5.0 mm. The improved microwave absorption is attributed to better impedance matching, high attenuation capacity and boosting dielectric polarization. The specific heterostructures comprised of FeCo core, Fe3O4 shell and graphene nanosheet carrier can induce abundant multiple heterogeneous interfaces, which can generate lattice distortion for dipolar polarization and introduce space charge separation for interface polarization. Theoretical calculation demonstrates that electrons transfer among the multiple interfaces and generate charge redistribution, leading to dipole and interface polarizations. Besides, the hybrids are hydrophobic, which can improve the stability of electric devices in wet. This work not only provides a point of view to boost the microwave absorption through dielectric polarization, but also gives a new insight to design environmentally friendly microwave absorbents by hydrophobic treatment. (C) 2021 Elsevier Ltd. All rights reserved.