Heterogeneous junctions of magnetic Ni core@binary dielectric shells toward high-efficiency microwave attenuation

Metal-organic-frameworks (MOFs) derived carbon-based composites with balanced impedance matching and synergistic dielectric/magnetic loss are considered as promising microwave absorbers. With the aim to promote interfacial polarization, herein, heterogeneous junctions composed of magnetic Ni core and binary dielectric shells (C and PEDOT) are synthesized by annealing Ni-MOFs precursors and an in-situ polymerization strategy, forming Ni@C@PEDOT spheres with multilayer heterogeneous interfaces. The results indicate that the final absorption attenuation is sensitive to the thickness of the dielectric PEDOT layer, when the thickness of the PEDOT layer is 224 nm, an optimal reflection loss of -72.4 dB is achieved at 2 mm and the effective absorption bandwidth reaches 6.4 GHz with a thickness of only 1.85 mm, the excellent absorption attenuation is accredited to the promoted impedance matching, enhanced conduction loss as well as the synergistic interfacial polarization induced by magnetic core and binary dielectric shells. Meanwhile, this work offers a simple and significant strategy in preparation for ideal microwave absorbers by rational design of multilayer heterogeneous interfaces.