Biomimetic\nPorous MXene-Based Hydrogel for High-Performance\nand Multifunctional Electromagnetic Interference Shielding

Abstract

Highly cross-linked hydrogels with water-enriched pores\nhave outstanding\npotentials for multifunctional architectures mimicking the biological\nmaterials with hierarchical structure in nature. Here, a type of transition\nmetal carbide (Ti₃C₂ MXene)/poly­(vinyl alcohol)\n(PVA) biomimetic hydrogels are manufactured via an ice-templated freezing\nfollowed by salting-out approach. In addition to high electrical conductivity\nand mechanical strength as well as ultraflexibility, a honeycomb-like\naligned porous structure is successfully achieved. Thanks to the synergistic\ninteractions among MXene, PVA, water, and biomimetic porous structure,\nthe thin hydrogels show an excellent X-band electromagnetic interference\n(EMI) shielding effectiveness (SE) of 57 dB at a merely 0.86 vol %\nMXene content. EMI SE more than 50 dB in the ultrabroadband frequencies\nof 8.2–40 GHz, covering typical GHz frequency ranges, is accomplished.\nMore importantly, via <i>in situ</i> controlling the water\ncontents of the hydrogels, a quantitative influence of the water on\nEMI shielding performance was ascertained. Furthermore, a good strain\nsensing performance of the ultraflexible, wearable hydrogel contributes\nto the sensitive and reliable detections of human motions and smart\ncoding. This work thus suggests an avenue for preparing robust, flexible,\nand multifunctional MXene-based biomimetic hydrogels toward high-performance\nEMI shields and wearable strain sensors.