Lightweight, Compressible, and Multifunctional Organic–Inorganic Nanofibrous Aerogels for Enhanced Microwave Absorption

Three-dimensional aerogels with ultralow density and extraordinary mechanical properties have attracted a lot of interest for their broad technological applications. Herein, lightweight, compressible, and multifunctional organic–inorganic nanofibrous aerogels are constructed by combining inorganic Fe7S8 doped honeycomb-like porous carbon nanofiber (Fe7S8/PCNF) and organic aramid nanofiber (ANF). The obtained Fe7S8/PCNF@ANF nanofibrous hybrid aerogels exhibit an interconnected lamellar structure, which endows the aerogels with an ultralow density of 0.014 g/cm3 and excellent compressibility of more than 95% compressive stress retention after 100 cycles at 40% strain. As an electromagnetic microwave absorber, the interconnected lamellar structure of aerogels, the homogeneously doped Fe7S8 nanosheets, and the honeycomb-like pores of carbon nanofiber enhance the impedance matching, enabling more microwaves to enter the aerogels to be dissipated. More importantly, the macroscopic lamellar network induces multiple reflecting and scattering to extend the transmitted pathways of microwaves, thus enhancing the attenuation ability of the absorber. When the mass-filling ratio of the materials to paraffin wax is 1:9, the obtained aerogels achieve a strong absorption of −37.0 dB at 15.7 GHz and a broad bandwidth of 5.52 GHz at a thickness of 2.0 mm. Meanwhile, the obtained aerogels present superior thermal insulation performance with thermal conductivity of 0.193 W/mK and outstanding hydrophobicity property with a water contact angle of 145°, guaranteeing the durable application of the absorber in extremely humid and high-temperature environments. This work may shed some light on designing new-generation microwave absorbing materials with multiple applications.