Scalable assembly of lightweight electromagnetic wave absorption aerogel via ion crosslinking and ambient pressure drying

Electromagnetic wave absorption (EWA) aerogels combine high porosity and large specific surface area, which reduce the effective dielectric constant and improve impedance matching, thereby enhancing EWA capability. However, most reported fabrication strategies rely on complex processes such as supercritical drying or freeze-drying, hindering large-scale production. Achieving both high EWA performance and scalable production remains challenging. Herein, we select carbon nanotubes (CNTs) as the dielectric loss phase, nickel ferrite (NiFe₂O₄) as the magnetic loss phase, and cellulose nanofibers (CNFs) as the skeleton to assemble a novelty CNT/NiFe₂O₄/CNF (CNC) aerogel through simple solvent exchange, ion crosslinking, and ambient pressure drying. Solvent exchange and Ca²⁺ coordination with carboxyl groups of CNFs and CNTs suppress capillary-induced structural collapse and maintain the porous network of the CNC aerogel during ambient drying. The introduction of CNTs enhances the conductive network and interfacial polarization, while maintaining favourable impedance matching. As the content of CNTs increases, the dielectric constant gradually rises, while the magnetic loss remained stable. The optimized CNC aerogel achieves the reflection loss of -55.62 dB at the frequency of 6.42 GHz with a matching thickness of 2.80 mm, and an effective absorption bandwidth that covers 10.65 GHz at a thickness of 1.53 mm. Radar cross-section simulations further confirmed its potential for practical EWA applications. The assembly strategy provides a scalable route to lightweight, broadband EWA aerogels.