Lightweight and recoverable ANF/rGO/PI composite aerogels for broad and high-performance microwave absorption

Graphene is regarded as an excellent microwave absorbing material due to its low density and adjustable dielectric properties. In this paper, aramid nanofiber/reduce graphene oxide/polyimide (ANF/rGO/PI) composite aerogels were successfully prepared by a two-step method of freeze-drying and annealing. ANF and PI enhance the bonding force between rGO sheets. The unique three-dimensional conductive network of rGO not only provides a transmission path for electrons, but also enhances multiple reflection and scattering for electromagnetic waves. The defects on the surface of rGO during annealing caused dipole polarization, and a large number of heterogeneous interfaces between ANF, rGO and PI enhance the interface polarization. Good dielectric properties and structure make the material have excellent microwave absorption properties. At 10.8 GHz, the minimum reflection loss (RLmin) reaches −41.0 dB, the effective absorption bandwidth covers the X-band, and the thickness is 5.1–6.9 mm. In addition, the material also exhibited good mechanical properties and heat resistance, and was expected to become a low-density, high-performance high-temperature microwave absorbing material.