Ultralight, highly compressible, thermally stable MXene/aramid nanofiber anisotropic aerogels for electromagnetic interference shielding

Abstract

Recently, improving the applicability of transition-metal carbon/nitride (MXene) shielding devices through integration with nanomaterials and polymers has gradually attracted the attention of researchers. Although the addition of an insulation enhancement phase improves the mechanical properties of MXene shielding devices, it is still a challenge to avoid extensive damage to the conductive network and the reduction of the shielding efficiency (SE). Herein, an effective approach is demonstrated to construct an ultralight, conductive Ti₃C₂T_x MXene/aramid nanofiber (ANF) anisotropic aerogel. Thanks to the strong interfacial interaction between the MXene nanosheets and ANFs, abundant rigid skeleton and “cell wall” structures were constructed in the anisotropic aerogel. The aerogel was not only endowed with excellent compressibility and superelasticity, but also built a macroscopic conductive network, thus increasing the impedance mismatch interface, and ensuring the electromagnetic interference (EMI) shielding performance of the device. At an ultra-low Ti₃C₂T_x content (0.58 vol%), the conductivity of the composite aerogel reached a maximum of 854.9 S m⁻¹ and the EMI SE reached 65.5 dB, which is the best efficiency value of an aerogel based on ANFs so far. In addition, the anisotropic Ti₃C₂T_x/ANF aerogel had consistent thermal stability and flame retardant properties. The nanosheet edge protection based on ANFs delayed the oxidation of MXene, and the EMI SE still reached 59.1 dB after 2 h of exposure in air at 250 °C. Therefore, the ultralight, superelastic, and thermally stable Ti₃C₂T_x/ANF anisotropic aerogel prepared in this work showed excellent application prospects in various extreme conditions.