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

Abstract

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 Fe3O4@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 Fe3O4@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 (RLmin) 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 Fe3O4 provided the bi-barriers towards corrosive medium. Then corrosion resistance of the electric circuit increased up to 3.56×107 Ω∙cm2 for FSA/Fe3O4@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.