Biomimetic Porous MXene-Based Hydrogel for High-Performance and Multifunctional Electromagnetic Interference Shielding

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