In-situ growth and pyrolysis of bimetallic CoFe-ZIF on carbon fibers for ultrathin and excellent electromagnetic wave absorption

Carbon fiber-based electromagnetic wave (EMW) absorbers are regarded as promising candidates for lightweight and multifunctional electromagnetic attenuation applications. However, the severe impedance mismatch arising from their excessive intrinsic electrical conductivity often restricts efficient broadband absorption at thin thicknesses. Herein, a hierarchical carbon fiber-based absorber is rationally designed via the in-situ growth of CoFe-Zeolitic Imidazolate Frameworks (CoFe-ZIFs) on carbon fiber surface, followed by controlled pyrolysis process to generate CoFe-derived magnetic nanoparticles. Benefiting from the optimized impedance matching and the synergistic contributions of dielectric loss, magnetic loss, and interfacial polarization, the CF@CoFe-600 composite achieves a remarkable minimum reflection loss (RLmin) of -67.47 dB at 10 wt% loading with a matching thickness of only 1.36 mm, together with a maximum effective absorption bandwidth (EAB) of 5.00 GHz, at a matching thickness of 1.28 mm. This work highlights that the rational integration of CFs with bimetallic MOF-derived magnetic phases offers an effective strategy for developing lightweight, ultrathin, and high-efficiency EMW absorbers.