Synergistically Constructed Electromagnetic Network of Magnetic Particle-Decorated Carbon Nanotubes and MXene for...

Lightweight polymer-based nanostructured aerogels are crucial for electromagnetic interference (EMI) shielding to protect electronic devices and humans from electromagnetic radiation. The construction of three-dimensional (3D) conductive networks is crucial to realize the excellent electromagnetic shielding performance of polymer-based aerogels. However, it is difficult to realize the interconnection of different conductive fillers in the polymer matrix, which limits the further improvement of their performance. Herein, 3D ordered hierarchical porous Fe₃O₄-decorated carbon nanotube (Fe₃O₄@CNT)/MXene/cross-linked aramid nanofiber (c-ANF)/polyimide (PI) aerogels were prepared via a unidirectional freezing strategy. Benefiting from the magnetic loss effect of Fe₃O₄ magnetic nanoparticles, the conductive and dielectric loss effects of CNTs, and the multiple reflections induced by the 3D ordered hierarchical porous structure, the Fe₃O₄@CNTs/MXene/c-ANFs/PI (FMCP) aerogels with the same contents of 8 wt % of Fe₃O₄@CNTs and MXene exhibit a high absolute EMI shielding effectiveness (SE) of up to 67.42 dB and a microwave reflection (SE) of 0.60 dB. More importantly, the phase transition of a small amount of MXene to TiO₂ optimizes the impedance matching and transmission and then improves the microwave absorption. The FMCP aerogel has an outstanding normalized surface specific SE (SSE/t) which is up to 62,654 dB cm²·g^-1. Meantime, the FMCP aerogels also show super-elasticity and could maintain 91.72% of the maximum stress after 1000 cycles of compression release under a fixed deformation of 60%.