Multi-scale porous bacterial cellulose/MXene/Fe3O4 aerogels via click chemistry for Ku-band electromagnetic absorption and thermal insulation

With a rapid advancement of electronic information technology, electromagnetic waves have facilitated information transmission, however, they have also increasingly caused severe electromagnetic interference affecting a normal operation of electronic devices. Consequently, the development of materials exhibiting high-efficiency electromagnetic wave absorption properties to mitigate electromagnetic pollution holds substantial scientific and practical significance. In this study, click chemistry was innovatively employed in the interfacial bonding of composite aerogels. Conductive MXene nanosheets were embedded within the three-dimensional network framework of bacterial cellulose (BC), and then the Fe 3 O 4 nanoparticles were attached to the surface of the substrate through a thiol-ene click chemical reaction, successfully constructing a BC/MXene/Fe 3 O 4 (BMF) composite aerogels with a multi-scale porous structure. The aerogel demonstrates a dual-loss mechanism, combining electrical loss and magnetic losses synergistically, thereby effectively addressing the issue of impedance mismatch. Additionally, its hierarchical pore structure significantly enhances multiple reflections and scattering of electromagnetic waves within the material, extending the propagation path and consequently improving energy dissipation capacity. The results show that the BMF composite aerogels exhibits excellent electromagnetic wave absorption properties. Its minimum reflection loss is −52.80 dB, the maximum effective absorption bandwidth is 5.98 GHz (11.91–17.89 GHz), and the absorption efficiency is 99.999 %, capable of covering most of the Ku band (2–18 GHz). Furthermore, the aerogel possesses lightweight characteristics (density of 0.0150 g/cm 3 ) and favorable thermal insulation properties (thermal conductivity of 0.0293 W·m −1 ·K −1 ). The development of BMF composite aerogels offers a novel approach for electromagnetic shielding materials applicable to the protection of precision electronic equipment and the defense industry applications.