Lightweight Ni Foam-Based Ultra-Broadband Electromagnetic Wave Absorber

Skin effect and high density are the main reasons that restrict the search of lightweight and high-performance metal-based electromagnetic (EM) wave absorbing materials. Although nanostructured metal materials have been fabricated to solve above problems, poor dispersibility and chemical stability issues brought about by high surface energy due to existing nano-size effect. In this work, lightweight Ni foam with NiO/NiFe₂O₄ in situ growth composites are fabricated by a facile and universal route as an effective alternative to high-performance metal-based EM wave absorber. Impressively, it is found that the foam structure and NiO/NiFe₂O₄/Ni components can synergistically boost EM wave absorption capacity. In detail, impedance matching from foam structure and energy dissipation from interfacial polarization and defect induced polarization provided by NiO/NiFe₂O₄ mainly contributes to its ultra-broadband EM wave absorption performance. As a result, the as-prepared sample (0.06 g·cm⁻³) delivers a wide absorption bandwidth of 14.24 GHz and thin thickness of 0.6 mm, as well as, high specific effective absorption bandwidth of 19444.4 GHz·g⁻¹·cm⁻². This work sheds light on the novel view on the synergistic effect of structure and components on EM wave absorption behaviors and demonstrates a new pathway for preparation of lightweight and high-performance metal-based EM wave absorbers.