Interface engineering of Fe/Fe3C@C magnetic-carbon composites for superior microwave absorption

Heterogeneous interfaces are crucial for enhancing the polarization loss in composite materials, thereby improving microwave absorption capabilities. However, creating well-defined multiple heterogeneous interfaces essential for optimal absorber performance presents a significant challenge. Herein, Fe/Fe 3 C@C magnetic-carbon composites featuring Fe-Fe 3 C-C multiple heterogeneous interfaces were fabricated through in-situ growth of Fe 3 O 4 on polydopamine nanospheres, followed by thermal reduction and carbonization. Owing to the controllable Fe-Fe 3 C-C multiple heterointerface design, the outer-layer magnetic components not only significantly improve impedance matching but also enhance the interface polarization loss. The optimized Fe/Fe 3 C@C-9–1 composite exhibits excellent microwave absorption performance, achieving a minimum reflection loss (RL min ) of −64.4 dB and a broad effective absorption bandwidth (EAB) of 6.0 GHz at a thin matching thickness of only 1.5 mm, surpassing neat carbon nanospheres and most magnetic-carbon materials. Additionally, simulations conducted using Computer Simulation Technology (CST) demonstrate that the Fe/Fe 3 C@C-9–1 coating significantly reduces radar cross-section (RCS), with values below −20 dB across nearly the entire frequency range of 2–18 GHz, highlighting its potential for radar stealth applications. This work provides a simple yet effective approach for tuning the interface properties of carbon-based materials, underscoring the promise of Fe-Fe 3 C-C multiple heterogeneous interfaces in the development of broadband, thin microwave absorbers.