Fe₃O₄/carbonized cellulose micro-nano hybrid for high-performance microwave absorber

A novel microwave absorber of Fe₃O₄/carbonized cellulose micro-nano hybrid with self-assembly porous structure has been fabricated through a facile process of loading of hydrolyzed Fe³⁺ polymers, freeze drying and annealing. Annealing temperature has effect on the microstructural defects and growth of Fe₃O₄ and graphite nanocrystals, and further affects the dielectric properties of Fe₃O₄/carbonized cellulose micro-nano hybrid. The Fe₃O₄/carbonized cellulose micro-nano hybrid annealed at 700 ℃ (FC-700) presents the most excellent microwave absorption properties. The effective adsorption bandwidth of FC-700 reaches up to 6.72 GHz with the thickness of 2.3 mm. The minimum reflection loss of FC-700 reaches -42.25 dB in frequency of 12.27 GHz. The delta-function method proves the Fe₃O₄/carbonized cellulose micro-nano hybrid has good impedance match with the free space. Cole-Cole plots validate the polarization relaxation. The novel carbon- based micro-nano hybrid with excellent performance, easy fabrication, and low cost has good prospects for microwave absorption application.