Ambient‐pressure‐dried (APD) preparation of transition metal carbide/nitrides (MXene) aerogels is highly desirable yet remains highly challenging. Here, ultrathin, high‐strength‐to‐weight‐ratio, renewable cellulose nanofibers (CNFs) are efficiently utilized to assist in the APD preparation of ultralight yet robust, highly conductive, large‐area MXene‐based aerogels via a facile, energy‐efficient, eco‐friendly, and scalable freezing‐exchanging‐drying approach. The strong interactions of large‐aspect‐ratio CNF and MXene as well as the biomimetic nacre‐like microstructure induce high mechanical strength and stability to avoid the structure collapse of aerogels in the APD process. Abundant functional groups of CNFs facilitate the chemical crosslinking of MXene‐based aerogels, significantly improving the hydrophobicity, water resistance, and even oxidation stability. The ultrathin, 1D nature of the CNF renders the minimal MXenes’ interlayered gaps and numerous heterogeneous interfaces, yielding the excellent conductivity and electromagnetic interference (EMI) shielding performance of aerogels. The synergies of the MXene, CNF, and abundant pores efficiently improve the EMI shielding performance, photothermal conversion, and absorption of viscous crude oil. This work shows great promises of the APD, multifunctional MXene‐based aerogels in electromagnetic protection or compatibility, thermal therapy, and oil‐water separation applications.

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Sustainable and renewable nanocellulose attracts more and more attention in various fields due to its high strength‐to‐weight ratio, small diameter, large aspect ratio, and abundant functional groups. The excellent properties and structural characteristics enabled a great potential of nanocellulose for efficient interactions with functional nanomaterials such as carbon nanotube, graphene, transition metal carbides/nitrides (MXenes), and metal nanoparticles, which is beneficial for preparing high‐performance electromagnetic interference (EMI) shields. We review the advances in the nanocellulose‐assisted preparation of composite films and aerogels for EMI shielding application. The nanocellulose‐based composites are evaluated in terms of their EMI shielding performance and the shielding mechanisms, including conduction, polarization, and multiple reflections are summarized. In addition to the constituent structure and contents, we highlight the significance of the microstructure design in enhancing the EMI shielding performance of the nanocellulose‐based EMI shields. Finally, the current challenges and outlook for these fascinating nanocellulose‐based EMI shielding composites are discussed.

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