Conjugated Microporous Polymer-Derived Nitrogen-Doped Carbon Nanocomposites with Multiple Magnetic Components for Broadband Microwave Absorption

Lightweight magnetic-carbon nanocomposites with multiple magnetic components are highly desirable for their efficacy in broadband microwave absorption. However, fabricating such composites with rationally designed chemical composites, tailored microstructure, and uniformly distributed magnetic components remains a grand challenge using conventional carbon precursors. Herein, we report the facile fabrication of porous N-doped carbon nanocomposites (Fe 3 O 4 @FeCN) with uniformly distributed and multiple magnetic components of Fe/Fe 3 C/Fe 3 O 4 nanoparticles using conjugated microporous polymers (CMPs) as the carbon precursor. CMPs have a high specific surface area and abundant nanoporosity, facilitating the efficient loading of iron ions and uniform growth of magnetic nanoparticles inside the carbon matrix. Notably, Fe 3 O 4 @FeCN-2 demonstrates excellent absorption capabilities with a minimum reflection loss (RL min ) of −49.68 dB and a wide absorption bandwidth of 5.72 GHz at a matching thickness of only 2.0 mm. This outstanding microwave absorption performance is primarily attributed to the synergistic effects of significantly improved impedance matching, enhanced polarization loss, and the introduction of magnetic loss through uniformly embedded Fe/Fe 3 C/Fe 3 O 4 nanoparticles in the nanoporous carbon matrix. Moreover, through simulation using computer simulation technology (CST), Fe 3 O 4 @FeCN-2 shows a significantly reduced radar cross section (RCS), with RCS values <−10 dB covering the entire frequency band of 2–18 GHz at angles of 30, 60, and 90°, demonstrating its great potential applications in radar systems and stealth technology. This work will inspire the development of carbon precursors to fabricate lightweight magnetic-carbon nanocomposites with precisely controlled structures for high-performance microwave absorption.