Magnetic nanoparticles deposition based on the peculiar pore structure of nanocellulose: preparation and properties of efficient thin-layer wave-absorbing materials.

The development of high-performance electromagnetic wave-absorbing materials is an important research topic for solving electromagnetic pollution. Cellulose is a low-cost and biodegradable natural biomass material, but the single dielectric loss mechanism of its carbonation product limits the wave absorption performance. Here, we propose a new strategy to construct hierarchical porous nanofibers with heterogeneous pore geometries (100-200 nm) by controlled carbonization of TEMPO-oxidized cellulose nanofibers. Magnetic Fe/Fe3O4 nanoparticles were embedded in these pores by a one-step annealing process using ferrocene as the iron source. The annealed composite (MF@C) offers dual-scale structural advantages: the unique heterogeneous structure of pores enhances multiple reflections of electromagnetic waves and interfacial polarization, and the magnetic nanoparticles are uniformly confined in the pores, synergistically optimizing impedance matching and magnetic dielectric loss. The MF@C-750 achieves an excellent reflective loss of -35.04 dB at a thickness of only 1.4 mm (RL < -10 dB) and an effective absorption loss of 3.44 GHz. 3.44 GHz effective absorption bandwidth (EAB). This performance is attributed to the synergistic interaction between the anisotropic porous carbon framework and magnetic nanoparticles. This study combines biomass-derived anisotropic porous carbon with confined magnetic nanoparticles, providing a sustainable pathway for the design of efficient microwave absorbers.