Ultrathin flaky FeSiAl and Fe3O4@C core-shell integrating the high-performance microwave absorber with gradient anti-corrosion barriers

Heterogeneous interface engineering and magnetic coupling are the main promising strategies for efficient microwave absorbers, but getting them stable in high-salt and humidity environments remains a challenge. Herein, we developed ultrathin flaky FeSiAl(FSA) integrating with Fe ₃O ₄@C core-shell for the high-performance microwave absorber with gradient anti-corrosion barriers. The Fe-Prussian blue analogue (PBA) derived microcubes decorated ultrathin FSA are prepared and transformed into Fe ₃O ₄@C core-shell in range of 500 ∼ 700 °C. The introduction of ferric oxide favors to impedance matching. Furthermore, the ultra-thin carbon layer and ferric oxide form a hybrid structure, which is conducive to enhancing electron spin and thereby enhancing microwave loss. This hybrid possess enhanced microwave absorption properties with a minimum reflection loss (RL _min) of −45.5 dB at 9.2 GHz at a thickness of 2.5 mm. Moreover, the maximum effective absorption bandwidth value reaches 5.2 GHz from 12.8 to 18 GHz at 1.6 mm. The gradient carbon layers and Fe ₃O ₄ provided the bi-barriers towards corrosive medium. Then corrosion resistance of the electric circuit increased up to 3.56×10 ⁷ Ω∙cm ² for FSA/Fe ₃O ₄@C-600. Meanwhile, the corresponding corrosion current decreased into 2.52×10 ⁻⁸ A∙cm ⁻². Hence, introducing multi-heterointerfaces and dual-magnetic components opens up a fantastic avenue for designing high-efficient absorbers with gradient anti-corrosion barriers.