Engineered heterointerfaces and defects in the PBA-derived NiFeSe@C nanocomposite for high-efficiency electromagnetic wave absorption

Abstract

Heterointerface engineering and defect manipulation have emerged as promising strategies for designing high-performance electromagnetic wave absorbers. Herein, a Prussian blue analogue (PBA)-derived selenide composite (NiFeSe@C) with a dual-phase crystalline structure (Fe_0.5Ni_0.5Se₂/Fe₂NiSe₄) is synthesized through a temperature-controlled selenization process. The hierarchical architecture, enriched with tailored heterointerfaces (Fe_0.5Ni_0.5Se₂@C and Fe₂NiSe₄@C) and selenium-rich vacancy defects, synergistically amplifies dipolar and interfacial polarization effects, thereby achieving high-efficiency electromagnetic wave attenuation. The engineered NiFeSe@C achieves minimum reflection loss values of −35.21 dB, −55.98 dB, and −34.04 dB in the C-, X-, and Ku-bands at thin thicknesses of 3.0 mm, 2.75 mm, and 1.80 mm, respectively. Notably, the material exhibits a broad effective absorption bandwidth of 4.55 GHz at a thickness of 1.80 mm. Radar cross-section (RCS) simulations demonstrated that shielding a perfect electric conductor with NiFeSe@C can achieve RCS reductions of 23.96 dB m², 42.83 dB m², and 30.65 dB m² in the C-, X-, and Ku-bands, respectively. This work elucidates the critical role of interfaces and defects that collectively govern dissipation mechanisms and establishes a blueprint for designing high-efficiency metal selenide absorbers, paving the way for rational defect-interface engineering in next-generation microwave-absorbing materials.