Lightweight three-dimensional porous aramid nanofibers/magnetic alloy nanoparticles hybrid aerogel for high-performance microwave absorption

Low density aerogels based on aramid nanofibers (ANFs) are promising candidate for microwave absorption materials. It is an arduous challenge to obtain lightweight microwave absorption materials with strong reflection loss (RL) and broad effective absorption bandwidth. In this paper, ANFs/FeCo hybrid aerogels were fabricated using ParaPhenylene TerephthalAmide (PPTA) as precursor via two-steps freeze-drying method, which offer three-dimensional network porous structure. ANFs/FeCo aerogel exhibited lightweight characteristic and excellent microwave absorption performance. The ultra-low density (14.35 mg cm^-3) of ANFs/FeCo aerogel was lower than the one of CNTs. The improvement of microwave absorption performance of ANFs/FeCo aerogels can be attributed to the three-dimensional network porous structure of aerogels and the introduction of magnetic FeCo alloys nanoparticles which can induce a cooperative effect of proper impedance matching, conduction loss, polarization loss, magnetic loss, and multiple scatting. The RL and effective absorption bandwidth of ANFs/FeCo aerogels can be adjusted via changing the mass ration of ANFs and magnetic FeCo nanoparticles. ANFs/FeCo-3 aerogel exhibited ultra strong RL (-60.62 dB) and broad effective absorption bandwidth (4.8 GHz) under a thin thickness (1.75 mm). Our work can provide new insight into the design of lightweight microwave absorption material.