Controlled phase and structure engineering-driven unique dielectric behavior enabling tailored electromagnetic attenuation

Modulating the phase composition and microstructural geometry in polymetallic metal-organic framework (MOF) derivatives represents a promising approach for achieving tunable electromagnetic response. However, deciphering the intrinsic phase-structure-property correlations in complex systems remains challenging. Herein, a competitive coordination and directed reduction strategy is employed to fabricate ternary Fe/Co/Zn (FCZ) composites with precisely controlled composition and architecture. Specifically, the topological structure progressively evolves from the inheritance of leaf-like precursors to hierarchical self-assembly and to final reconfiguration. Introducing Fe into the original Co/Zn bimetallic system progressively suppresses the Co₃ZnC phase while promoting the formation of the Fe-Co solid solution and amorphous ZnO. The construction of multiple heterointerfaces and high-density defects within nitrogen-doped carbon substrates facilitates the coupling effect of multiple polarization loss mechanisms. This synergistic effect induces an anomalous dielectric behavior, characterized by attenuated polarization relaxation peaks concurrent with enhanced polarization response. Consequently, the optimized FCZ4 demonstrates exceptional electromagnetic wave absorption performance, featuring an ultra-low reflection loss of −84.41 dB and an ultra-broad bandwidth of 6.08 GHz. Gradient regulation of Fe content enables the realization of tunable frequency response characteristics spanning the low-to-high frequency range. This work establishes a generalized phase-structure-dielectric correlation model, offering new insights into tailorable electromagnetic attenuation in multi-metallic systems.