CNTs decorated Fe₃O₄/Co–Ni polyhedrons with heterogeneous interfaces for promoting microwave absorption

The pursuit of outstanding microwave absorption (MA) absorbers to mitigate excessive electromagnetic pollution presence attracted considerable research interest. Magnetic metal particles modified with metal-organic frameworks (MOFs) and carbon nanotubes (CNTs) offer synergistic benefits and can be integrated into innovative composites with outstanding MA properties, particularly when employed in thin matching thicknesses. Herein, we synthesized FCN@CNTs composites comprising Fe₃O₄/Co–Ni polyhedrons (FCN) via hydrothermal and pyrolytic processes. The incorporation of Fe₃O₄ particles loaded with MOFs derivatives proves beneficial in establishing multiple transmission paths for electromagnetic waves (EMW). Simultaneously, the introduction of 3D crosslinked CNTs enhances the composite's conductive loss, promotes strong interfacial polarization, and induces dual dielectric/magnetic loss. The abundant homogeneous interfaces and dielectric/magnetic synergies of the Fe₃O₄/Co–Ni polyhedrons contribute to the impedance matching. For FCN@CNTs absorbers at 11.12 GHz, the minimum reflection loss (RL_min) reaches −46.6 dB, with an absorption bandwidth of 6.4 GHz corresponding to a matching thickness of 1.9 mm. Across a thickness range of 1.3–4.0 mm, the absorption intensity remains below −30 dB. Furthermore, the electronic distribution properties at the heterogeneous interfaces in FCN@CNTs are elucidated through density functional theory (DFT) calculations. The aggregation and distribution of electrons at non-uniform interfaces facilitate electron transfer channels, indicating the presence of interfacial polarization and enhancing the dielectric loss of FCN@CNTs. Henceforth, this work presents a new research method for MOFs based MAMs with thin thicknesses and broad bandwidth.