Microstructure-engineered FeOx@C composites with synergistic loss mechanisms for remarkable electromagnetic microwave absorption performance

Iron-doped carbon composites are prepared as microwave absorbing materials. • Remarkable microwave absorption is achieved via synergistic loss mechanisms. • The dual absorption mechanism involves dielectric and magnetic losses. • Controlling the calcination temperature allows tuning losses and impedance matching. • The optimized Fe 3 O 4 @C composite achieves an exceptional minimum reflection loss. : The pursuit of lightweight, high-performance, broadband, thin electromagnetic wave–absorbing materials has attracted considerable research attention in the context of addressing electromagnetic pollution and interference issues. Herein, we prepare iron-doped carbon composites (FeO x @C) via a hydrothermal method and controlled calcination, achieving remarkable electromagnetic wave absorption performance through synergistic loss mechanisms. By adjusting the calcination temperature, the granular microstructure, including Fe 3 O 4 crystallinity/morphology and carbon graphitization/defects, was precisely controlled to balance conductive/magnetic losses and optimize impedance matching for optimal performance. A large reflection loss peak of −44.8 dB, correlating to nearly 99.99% absorption efficiency, is obtained with a 2.5-mm-thick Fe 3 O 4 @C nanorod absorber at an effective absorption bandwidth ( RL < −10 dB) of 3.92 GHz (9.76–13.68 GHz). Important relationships are revealed between the reflection loss peak value (RL), absorption peak frequency, and effective absorption bandwidth (EAB), with respect to the overall thickness of the Fe 3 O 4 @C nanorod absorber. The HFSS Electromagnetic simulations were conducted to verify the above experimental findings. The results demonstrate that the Fe 3 O 4 @C composite coating achieves the lowest radar cross-section (RCS) over a wide angular range compared to Fe 2 O 3 @C and Fe@C, verifying its superior microwave absorption performance. This research achievement holds particular importance in the context of mitigating radiation interference in 5G technology and enhancing shielding absorption of X-band radar waves.