Ambient-pressure-dried cellulose-based hierarchical composite with high-efficiency dual-spectra compatible defense

Modern infrared detection technology and electromagnetic interference (EMI) problems spur the development of multispectral compatible defense materials. However, high-performance materials prepared with facile preparation technology are in urgent demand. Herein, we proposed a cellulose-based asymmetric hierarchical composite for dual-spectra compatible defense (i.e., EMI shielding and infrared stealth). This hierarchical composite was assembled with a TEMPO oxidized cellulose nanofiber (TOCNF)/carbon nanotube (CNT) aerogel prepared by ambient pressure drying and a TOCNF/MXene film. The assembled composite realized a maximum EMI shielding effectiveness (EMI SE) of 77.3 dB, and the absorption coefficient could reach 0.71 at most, benefiting from an “absorption-reflection-reabsorption” shielding mechanism. This composite acted as an absorption-dominated EMI shielding material that effectively mitigated the secondary reflection of electromagnetic waves. Interestingly, the asymmetric structure allowed this composite to switch to a reflection-dominated EMI shielding material when flipped easily. Furthermore, the composite exhibited outstanding infrared stealth performance, attributed to the impeded heat transfer within the aerogel layer and the inherently low infrared emissivity of the film layer. This asymmetric hierarchical structural design, based on ambient pressure drying, offers a facile strategy for developing dual-spectra compatible defense materials with switchable electromagnetic wave absorption capability.