FeCo alloy nanoparticle decorated cellulose based carbon aerogel as a low-cost and efficient electromagnetic microwave absorber

Abstract

Recently, low-cost biomass based carbon aerogels have turned out to be promising efficient electromagnetic wave (EMW) absorption materials, but the bad impedance matching and single loss mechanism often result in poor EMW absorption properties. In this study, magnetic FeCo alloy nanoparticle decorated cellulose-based carbon aerogel (FeCo@CCA) was prepared by calcining the cellulose aerogel with homogeneously dispersed CoFe₂O₄ particles (CoFe₂O₄@CA), which was the freeze-dried product of hydrothermal treated Fe²⁺/Co²⁺ metal ion absorbed cellulose hydrogel. Here, the hydrothermal synthesis method can effectively ensure the even dispersion of the calcination product of magnetic FeCo alloy nanoparticles, which is conducive to good impedance matching, additional magnetic loss, and improved dielectric loss. Besides, the porous structure of the aerogel can also result in multi-reflection/scattering to attenuate more the incident EMW. As a result, the EMW absorption properties of the prepared FeCo@CCA can be effectively tuned by changing the metal ion concentration, and the product arising from a metal ion concentration of 100 mmol L⁻¹ (FeCo@CCA-100) displays the strongest EWM absorption capacity with a minimum reflection loss (RL_min) of −49.5 dB at a thickness of 4.05 mm at 9.84 GHz and a maximum effective absorption bandwidth (EAB_max, RL < −10 dB) of 10.88 GHz (6.96–17.84 GHz), covering the whole Ku and X band and almost half of the C band. This study provides a guideline for developing efficient cellulose-based carbon aerogel based EMW absorbers.