N atoms regulate heterogeneous crystal phase engineering of mesoporous magnetic FexN nanofibers to promote electromagnetic wave dissipation of magnetic composite aerogel absorbers

One dimensional (1D) soft magnetic nanomaterial and its lightweight porous composites are highly needed in promoting electromagnetic wave absorption for the high-frequency magnetic response and low density. In this study, lightweight magnetic composite aerogels were fabricated through the process of heterogeneous crystal phase, involving the modulation of 1D mesoporous magnetic FexN nanofibers with N atoms. The promotion of electromagnetic wave dissipation was achieved through meticulous composition design and interface optimization. The multi-mode magnetic resonance of 1D heterogeneous crystal FexN magnetic nanofibers, along with the N-doped reduced graphene/amorphous carbon three-dimensional conductive network, greatly enhances electromagnetic wave dissipation through the magnetic-dielectric synergistic effect. Consequently, the resulting composite absorber demonstrates remarkable microwave absorption capabilities, achieving a maximum effective absorption bandwidth (EABmax) of 6.63 GHz at a thickness of 2.13 mm, and a minimum reflection loss (RLmin) of −63.3 dB. In addition, the composite magnetic aerogel with the best microwave absorption performance shows a low density of 11.25 mg/cm3. This electromagnetic synergy approach is anticipated to serve as a guide for the development of highly efficient lightweight magnetoelectric composite for wideband microwave absorption in the future.