Abstract: Hydrogen-substituted graphdiyne (HsGDY) is a novel dielectric loss-dominant microwave-absorbing material. It plays a critical role in advancing electromagnetic wave (EMW) attenuation through synergistic component interactions and rational structural design. In this study, we propose a strategy to enhance heterogeneous interfaces and magnetic loss by utilizing MnO₂ nanowires as one-dimensional rigid templates, polydopamine (PDA) as interfacial modifiers, and Ni-based metal-organic frameworks (Ni₃(btc)₂) as magnetic hybrid precursors. These components were integrated to construct hierarchical MnO₂@HsGDY@PDA@Ni₃(btc)₂ composite fibers. The fibers were subsequently subjected to vacuum carbonization to yield MnO@HsGDY@NC/Ni magnetic nanofibers with both dielectric and magnetic loss capabilities. Systematic investigations on the effect of Ni₃(btc)₂ loading revealed that indirect modulation of Ni nanoparticle content enables precise control over the electromagnetic parameters of the nanofibers. Increasing Ni nanoparticle content significantly improved the material's EMW dissipation capacity. The synthesized MnO@HsGDY@NC/Ni-4 exhibits superior EMW absorption performance, achieving a minimum reflection loss (RL_min) of -48.47 dB@2.5 mm with 35 % filler loading and an effective absorption bandwidth (EAB) of 4.9 GHz (12.9-17.8 GHz). Research on the absorption mechanism reveals that the introduction of multiple heterogeneous interfaces significantly enhances interfacial polarization and multi-scattering effects, while component synergy optimizes impedance matching. Furthermore, magnetic Ni nanoparticles introduce additional loss mechanisms, including natural resonance and eddy current effects, collectively enhancing the EMW absorption performance of MnO@HsGDY@NC/Ni magnetic nanofibers.

Key words: Hydrogen-substituted graphdiyne, Core-shell structures, Magnetic nanofibers, Electromagnetic wave absorption