Template Engineering of Magnetic Nanoparticles Decorated on Porous Carbon for High‐Performance Multiband Electromagnetic Wave Absorption

ABSTRACT Although magnetic carbon materials possess significant potential in the field of electromagnetic wave absorption (EWA) due to the synergistic effect of multiple attenuation mechanisms, the currently reported magnetic carbon EWA materials face some challenges, such as high cost, low yield, and easy agglomeration of the magnetic component, making it difficult to meet the requirements of novel EWA materials. To this end, the three‐dimensional porous carbon skeleton loaded with well‐controlled Fe 3 O 4 nanoparticles (Fe 3 O 4 /PC) was fabricated via the salt template strategy, demonstrating the bifunctional effects in pore structure construction and magnetic particle loading. Benefiting from dielectric loss, magnetic loss, and multiple reflections, the as‐prepared magnetic carbon material achieves efficient absorption exceeding −25 dB over the multiband range (C, X, and Ku bands) at the filler loading of 8.75 wt%. Especially, it delivers remarkable performance of −64.4 dB at 1.71 mm and a 5.4‐GHz effective absorption bandwidth. What is more, the maximum radar cross‐sectional reduction of 27.5 dB m −2 also testifies to its excellent performance. When filled with thermoplastic polyurethane, the obtained flexible film also exhibits high‐performance absorption at a low filler level. Surprisingly, because of the high yield of petroleum coke, this magnetic carbon material can be successfully scaled up. Therefore, this work provides a new avenue for the scale‐up preparation and practical application of lightweight magnetic carbon absorbers.