Nanocellulose‐MXene Biomimetic Aerogels with Orientation‐Tunable Electromagnetic Interference Shielding Performance

Abstract

Designing lightweight nanostructured aerogels for high‐performance electromagnetic interference (EMI) shielding is crucial yet challenging. Ultrathin cellulose nanofibrils (CNFs) are employed for assisting in building ultralow‐density, robust, and highly flexible transition metal carbides and nitrides (MXenes) aerogels with oriented biomimetic cell walls. A significant influence of the angles between oriented cell walls and the incident EM wave electric field direction on the EMI shielding performance is revealed, providing an intriguing microstructure design strategy. MXene “bricks” bonded by CNF “mortars” of the nacre‐like cell walls induce high mechanical strength, electrical conductivity, and interfacial polarization, yielding the resultant MXene/CNF aerogels an ultrahigh EMI shielding performance. The EMI shielding effectiveness (SE) of the aerogels reaches 74.6 or 35.5 dB at a density of merely 8.0 or 1.5 mg cm ^–3, respectively. The normalized surface specific SE is up to 189 400 dB cm ² g ^–1, significantly exceeding that of other EMI shielding materials reported so far.

Abstract

Oriented biomimetic hybrid cell walls of nanocellulose‐MXene aerogels for tunable electromagnetic interference shielding and mechanism are represented by a yin‐yang symbol. Herein, the blue and red regions in the symbol correspond to angles with a smaller and larger transmission of the incident EM waves, respectively.