Ultra-adhesive and tough Ti₃C₂T_x/cellulose hydrogels for highly efficient microwave absorption

Conventional microwave absorption (MA) hydrogels suffer from inadequate interfacial adhesion, limited mechanical robustness, and narrow absorption bandwidths. Herein, a low-cost zinc chloride hydrate/formic acid deep eutectic solvent was employed to dissolve microcrystalline cellulose (MCC) at room temperature, enabling the synthesis of a MXene/MCC/PAM (MX-C) hydrogel. This hydrogel exhibited enhanced MA capability, adhesive performance, and mechanical strength. After optimizing the concentration of the MXene dispersion to 3.0 wt%, the MX-C hydrogel (without any magnetic component) achieved exceptional MA performance at 2 mm thickness with a reflection loss of less than -10 dB over the entire X-band and a minimum reflection loss of -28 dB. The MA performance arises mainly from conduction loss, aided by polarization and internal reflections. Benefiting from the abundant hydrogen bonds of MCC, MX-C hydrogel demonstrated excellent adhesiveness with adhesion strength as high as 2.13 MPa, enabling its direct attachment to various substrate surfaces without additional binders. MX-C hydrogel also exhibited exceptional deformability with a tensile strain of 524 % and a compressive strain of 47 %. This multifunctional hydrogel integrates strong adhesion, broadband MA, and mechanical flexibility to provide an innovative solution for flexible electromagnetic stealth devices, as well as intelligent camouflage systems.