Lightweight, superhydrophobic, and superelastic MXene/carboxymethylcellulose sodium composite aerogels for efficient and multifunctional electromagnetic interference shielding

MXene-based aerogel has shown great application potential in electromagnetic interference (EMI) shielding because of its low density and low reflection efficiency. However, the fabrication of MXene-based aerogels for EMI shielding with exceptional elasticity, compressibility, and durability remains a challenge because of the limited mechanical property and oxidation behavior of MXene. Here, MXene/carboxymethylcellulose sodium composite aerogels were prepared by using unidirectional freezing combined with binary organosilane cross-linking. The composite aerogel with a MXene content of 90 % displayed an exceptional EMI shielding efficiency (45.8 dB) at a super low density (19.75 mg/cm 3 ), and the density-normalized shielding efficiency achieved a high level of 11,595 dB·cm 2 /g. The modification of organosilanes endowed the cross-linking network formed in the composite aerogel with great elasticity and compressibility. The organosilanes also helped the aerogel build a superhydrophobic surface, leading to a contact angle of 151.5°. Given the excellent superhydrophobicity and mechanical properties, the aerogel could maintain its EMI shielding performance after being dipped in water or compressed for 100 times. Furthermore, the aerogel prepared in this study possessed thermal insulation performance and piezoresistive feature. This study provides a convenient strategy to fabricate multifunctional MXene-based aerogels with low density, elasticity, and durability, which shows great application potential in the fields of EMI protection, thermal management, wearable devices, and smart sensors.