Dual Cross‐Linked Magnetic MXene Aerogel with High Strength and Durability Enables Multifunctionality

Abstract The construction of lightweight yet robust, durable magnetic transition metal carbides and/or nitride (MXene) aerogels is highly desired for assembling high‐performance, multifunctional architectures. However, the fabrication and application of magnetic MXene aerogels is severely restricted by their inferior mechanical strength and poor water/oxygen resistance. Here, sustainable cellulose nanofibrils (CNFs) are employed for assisting in the physical and chemical dual cross‐linking to strongly bind the MXenes and MOF‐derived magnetic nanoparticles. The dual‐crosslinked magnetic MXene aerogels (D‐MMAs) achieve a density as low as 12 mg cm −3 , and acquire a significantly improved mechanical strength of up to 1311% over physically crosslinked ones, as well as remarkably improved hydrophobicity, and oxidation stability. Furthermore, the multifunctional integration of efficient and tunable electromagnetic wave (EMW) absorption, remarkable photothermal conversion, thermal insulation, prominent oil‐water separation, thin/thick oil and dye absorption capability, and the remote magnetic controllability is accomplished. Notably, the D‐MMA performs a maximum absorption intensity of −63.9 dB, and accomplishes a specific reflection loss of −1105 dB mm −1 , comparable to the best MXene‐based EMW absorbers ever reported. Given its facile, scalable, and sustainable manufacturing approach, the multifunctional D‐MMAs hold great application prospects in various fields of next‐generation electronics, special equipment protection, defense, and aerospace.