Multifunctional ultralight magnetic CNFs/MXene/Fe3O4 nanodiscs aerogel with superior electromagnetic wave absorption performance

The design of innovative microstructures and the implementation of an appropriate multi-component strategy remain challenging in the development of advanced electromagnetic wave (EMW) absorbing materials. Achieving strong absorption and a wide effective absorption bandwidth while maintaining a thin sample thickness and low filling level is particularly demanding. Herein, a three-dimensional (3D) dielectric cellulose nanofiber (CNF)/Ti3C2Tx MXene carbon aerogel, incorporating magnetic Fe3O4 nanodiscs (NDs), was fabricated using a directional-freezing technique followed by reduction. Surprisingly, the reduction process activates the multifunctional application of aerogel with better elasticity and greatly improved electromagnetic properties, killing two birds with one stone. The structured cellular arrangement and the presence of diverse dielectric/ magnetic interfaces contribute to the exceptional absorption capabilities by facilitating optimal impedance matching, enabling multiple polarization modes, and fostering electric/magnetic coupling phenomena. The aerogel exhibits excellent microwave absorption properties, characterized by its ultra-lightweight (3 % of filling ratio and 4.65 mg cm-3 of density), ultra-thin (2.18 mm), ultra-wide frequency band (6.68 GHz) and strong absorption (-56.8 dB). Additionally, the aerogel provides attractive functions such as thermal insulation and great mechanical properties (100 % recovery after 1000 cycles under 50 % strain). This study lays the groundwork for the advancement of microwave-absorbing materials, showcasing their vast potential for multifaceted applications.