Double crosslinked network aerogels with electromagnetic synergy for tunable electromagnetic wave absorption

Aerogels with low reflection and high performance are ideal for blocking electromagnetic radiation and pollution. Nevertheless, the development of such materials featuring precisely balanced magnetic/dielectric multicomponent systems, and integrated multifunctionality remains a major challenge. In this work, cellulose nanofiber reinforced polyvinyl alcohol was prepared as a pore wall via a bio-inspired strategy. Double-effect aerogels were prepared by coating magnetic Ni with polyvinyl alcohol and supporting graphene with cellulose nanofibers. Optimizing the composite ratio of magnetic/dielectric components could regulate electromagnetic parameters and achieved excellent electromagnetic wave attenuation performance. CG10/PN20 achieved a low reflection coefficient (R = 0.36), and the average electromagnetic interference shielding effectiveness could reach 35.46 dB. The internal electron transfer was enhanced, and charge agglomeration, rearrangement and dipole polarization promoted the generation of polarization loss via good dielectric properties and rich effective interface between metal Ni and graphene sheets. The minimum reflection loss of CG15/PN15 reached − 45.39 dB (3.7 mm), and the effective absorption bandwidth was 4.1 GHz, which provided a way to realize the unification of high electromagnetic interference shielding and absorption. In addition, the CG/PN aerogels exhibited excellent mechanical properties, thermal stability and flame retardancy.