Integrating Sulfur Doping with a Multi‐Heterointerface Fe7S8/NiS@C Composite for Wideband Microwave Absorption

Heterointerface engineering is presently considered a valuable strategy for enhancing the microwave absorption (MA) properties of materials via compositional modification and structural design. In this study, a sulfur‐doped multi‐interfacial composite (Fe7S8/NiS@C) coated with NiFe‐layered double hydroxides (LDHs) is successfully prepared using a hydrothermal method and post‐high‐temperature vulcanization. When assembled into twisted surfaces, the NiFe‐LDH nanosheets exhibit porous morphologies, improving impedance matching, and microwave scattering. Sulfur doping in composites generates heterointerfaces, numerous sulfur vacancies, and lattice defects, which facilitate the polarization process to enhance MA. Owing to the controllable heterointerface design, the unique porous structure induced multiple heterointerfaces, numerous vacancies, and defects, endowing the Fe7S8/NiS@C composite with an enhanced MA capability. In particular, the minimum reflection loss (RLmin) value reached −58.1 dB at 15.8 GHz at a thickness of 2.1 mm, and a broad effective absorption bandwidth (EAB) value of 7.3 GHz is achieved at 2.5 mm. Therefore, the Fe7S8/NiS@C composite exhibits remarkable potential as a high‐efficiency MA material owing to the synergistic effects of the polarization processes, multiple scatterings, porous structures, and impedance matching. To address the electromagnetic hazards, a multi‐interfacial Fe7S8/NiS@C composite is fabricated using NiFe‐LDH coating and high‐temperature vulcanization. It possesses porous structure and rich defects, and exhibite an RLmin value of −58.1 dB at a thickness of 2.1 mm. Furthermore, the electromagnetic simulation experiment and RCS simulation indicate that the multi‐interfacial Fe7S8/NiS@C composite has a superior MA ability.