Micro-helical Ni3Fe chain encapsulated in ultralight MXene/C aerogel to realize multi-functionality: Radar stealth, thermal insulation, fire resistance, and mechanical properties

Magnetic carbon aerogels with high porosity, ultralow density, and excellent impedance matching are considered to be a promising microwave absorption (MA) material. In this study, ethylene glycol polymerization is used to assemble Ni3Fe particles into a micro-helical chain, which is further wrapped by MXene and then encapsulated in poly-Schiff-base aerogels through the carbonyl–amine condensation reaction. Finally, ultralight TiO2/Ni3Fe/MXene/C (NFMC) aerogels are synthesized through calcination treatment. Benefiting from the electromagnetic synergistic effect of multi-dimensional and multi-component materials, the NFMC-7 aerogel exhibits excellent MA performance with a minimum reflection loss of −61.6 dB at 3.0-mm thickness and an effective absorption bandwidth of 8.16 GHz at 2.77-mm thickness under a low filler loading of 7.6 wt%. Commercial computer simulation technology is used to verify the strong magnetic and dielectric loss characteristics of Ni3Fe chains. At the same time, the NFMC-7 aerogel exhibits excellent radar stealth, heat insulation, compression resistance, and fire resistance performance, which verifies its practical applicability. Overall, this work establishes an effective strategy to fabricate multi-functional magnetic aerogels, which can serve as lightweight, thin, and strong microwave absorbers with broad absorption bandwidth.