Embedded Ni/NiO Heterostructure in MoO3–x Nanorods toward Reinforced Interfacial Polarization for Electromagnetic Wave Absorption

Heterostructure design has been recognized as a promising strategy to reinforce the dielectric polarization response through the strengthened heterogeneous interface interaction. However, the controllable preparation of homogeneously distributed heterostructures in absorbers remains a great challenge. Herein, we proposed a moderate reduction strategy to synthesize a NiO/Ni heterostructure tightly embedded in MoO3–x nanorods in situ by controlling phase evolution of NiO to metallic Ni under the H2/Ar atmosphere. Profiting from the abundant NiO/Ni heterostructures that induced electron migration and redistribution at NiO/Ni interfaces, the NiO/Ni/MoO3–x absorbers show a strengthened interfacial polarization relaxation response. Enriched oxygen vacancies serve as dipole polarization centers to form independent electric dipole pairs, which are conductive to the enhancement of dipole polarization loss under the alternating electromagnetic filed. Additionally, the homogeneously distributed magnetic Ni species construct a magnetic coupling network and generate ferromagnetic resonance and eddy current loss to boost magnetic loss. Consequently, the resultant absorbers display superior electromagnetic wave absorption performances with a minimum reflection loss value of −64.18 dB and maximum absorption bandwidth up to 6.6 GHz with a thickness of 1.8 mm, effectively covering the whole Ku-band. The radar cross-section (RCS) simulations demonstrate the excellent radar signal suppression capability of NiO/Ni/MoO3–x absorbers and the maximum RCS reduction value reaching 21.3 dB at 0°. The obtained absorption properties almost surpass most of the reported composites with embedded heterostructures. This work provides a strategy for the preparation of multiple heterogeneous interfaces and presents a deep insight into the attenuation mechanisms of absorbers.