In Situ Growth Medium Entropy Alloy Nanoparticles on the Ordered Structure Carbon Nanofiber Aerogel for Enhanced Microwave Absorption and Infrared Stealth Properties

Bacterial cellulose (BC)-derived carbon nanofiber aerogel shave promising applications in the field of electromagnetic wave (EMW) absorption. However, the high permittivityinduced poor impedance matching and the single loss mechanism lead to weak EMW absorption performance. Assembling into the ordered structure can establish a continuous conductive network, thereby augmenting the conductive loss and enriching the loss mechanisms. Herein, an ordered structure carbon nanofiber aerogel anchored with FeCoNi medium entropy alloy (MEA) nanoparticles (CNA@FeCoNi) is fabricated via directional freeze-drying and hydrogen thermal reduction strategy. The incorporation of FeCoNi MEA nanoparticles can not only introduce magnetic loss but also enhance impedance matching by reducing the dielectric constants. In addition, FeCoNi MEA nanoparticles trigger strong polarization loss due to the lattice distortion arising from the multi-component composition. Consequently, the fabricated CNA@FeCoNi presents remarkable EMW absorption performances with the minimum reflection loss (RL_min) value of -56.7 dB at an ultra-low filler of 5 wt.% and the effective absorption bandwidth (EAB) reaches 5.28 GHz. Besides, radar cross-section (RCS) simulation analysis and infrared radiation (IR) images deliver excellent application potential for both civilian and military purposes.