Synthesis and mechanism investigation of wide-bandwidth Ni@MnO₂ NS foam microwave absorbent

Lightweight and easily available foams used for microwave absorption are hotspots for preventing electromagnetic (EM) pollution. In this paper, we focused on a novel kind of Ni-based foam that modified by MnO₂ nanosheets (denote as Ni@MnO₂ NS foam) was synthesized by a facile hydrothermal reaction, then analyzed by XRD, XPS and SEM characterization techniques. The Ni@MnO₂ NS foam possess excellent microwave absorption performance (MAP). In details, the superb reflection loss (RL) was up to −37.55 dB with the coating thickness of 3.6 mm and ultra-wide effective absorption (RL < −10 dB), suggesting 90% EM wave were attenuated, which could reach 11.2 GHz (from 6.8 GHz to 18 GHz). Meanwhile, the EM wave attenuation mechanism was discussed and it was proposed that the prominent MAP could be responsible for magnetic loss (natural resonance of Ni frameworks) and dielectric loss (interface polarization and dipole polarization). Ni@MnO₂ NS foam is a multifunction material that not only can be used in controlling EM pollution but also has potential application in other fields.