Defect-Engineered Graphene/Si₃N₄ Multilayer Alternating Core-Shell Nanowire Membrane: A Plainified Hybrid for Broadband Electromagnetic Wave Absorption

To tackle the increasing electromagnetic pollution, broadband electromagnetic wave (EMW) absorption materials are urgently needed. Toward this goal, traditional strategies resort to the construction of multicomponent dielectric/magnetic hybrid materials, including ternary, quaternary, or even more complicated systems. However, they always suffer from many intrinsic drawbacks in practical applications. Herein, a theory-directed strategy is presented to design plainified EMW absorption materials (binary hybrids) via amplified interface effects, which are based on well-designed multilayer alternating core-shell nanostructures by chemical vapor deposition (CVD). A defect-engineered CVD graphene (DG) core composed of graphitic open edges and in-plane defects is used as a lossy phase. Correspondingly, a CVD Si₃N₄ layer with nanometer thickness is used as an impedance matching shell. By optimizing the alternating numbers of DG/Si₃N₄ units, enhanced interface polarization and strong frequency dispersion behavior of permittivity (especially the real part, ε′) are obtained, which helps the plainified binary hybrids to reach an effective absorption bandwidth (EAB) of 8.0 GHz at a thickness of 2.7 mm. Moreover, these plainified hybrids show excellent thermal and pH stability. Even after 1000 °C oxidation, for example, an EAB of 7.44 GHz coupling with a minimum reflection coefficient of −77.3 dB is still achieved.