Construction of ZnS/ZnIn ₂ S ₄ /CF via Defect and Interface Engineering for Efficient Electromagnetic Wave Absorption

The strategic construction of interfacial and defect engineering has significantly improved the design and application of high‐performance electromagnetic wave (EMW) absorbing materials. This study reported a novel three‐dimensional (3D) porous sheet‐like ZnS/ZnIn 2 S 4 /CF composite featuring abundant heterointerfaces and sulfur vacancies (S vacancies). By precisely controlling the indium addition and employing plasma treatment, the morphology, interface structure, and vacancy concentration were synergistically tuned. The unique 3D porous architecture, coupled with rich heterointerfaces and S vacancies, facilitated superior impedance matching while substantially enhancing interfacial and dipolar polarization. Plasma treatment further increased S vacancy concentration, thereby boosting dipolar polarization. Consequently, the optimized composite (ZISC‐2′) achieved exceptional EMW absorption performance with a minimum reflection loss (RL min ) of −82.4 dB at a low filler loading of merely 5.0 wt.% and an effective absorption bandwidth of 4.4 GHz across the Ku‐band. This work advances the dual‐regulation strategy of interfaces and defects, offering a promising pathway for developing high‐performance metal sulfide‐based EMW absorbers.