Interfacial [Ti-O-M] bonds reinforced delectric responses in MXene/transition metal sulfide aerogels for efficient electromagnetic wave attenuation

Ti 3 C 2 T x MXene aerogels with the advantages of better wave impedance matching and lightweight toward electromagnetic wave (EMW) protection have aroused widespread attention. However, the limited gelation capability and inadequate interfacial interactions between MXene nanosheets impose insurmountable challenges to construct robust, free-standing MXene monoliths with efficient absorption capability. Herein, a universal assemble-confinement strategy is presented to fabricate spatially dispersed transition metal sulfides anchored on MXene aerogels (MXene/TMS) via interfacial Ti-O-M bonds, in which the divalent metal ions (Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ ) mediate the rapid gelation and assembly of MXene nanosheets into hydrogels, followed by the topological transformation of sulfidation treatment. Benefiting from the macroscopic porous structure, intimate interfacial interactions generated by Ti-O-M bonds between MXene skeleton and metal sulfides, and numerous defect polarization sites, MXene/TMS aerogels deliver optimal impedance matching balance and enhanced attenuation capacities compared to MXene nanosheets. Specifically, MXene/CoS aerogels show remarkable EMW absorption performances, with a minimum reflection loss value of −69.6 dB and full X-band (8.2–12.4 GHz) absorption at an ultralow density of 0.021 g/cm 3 . Experimental results and simulation analyses demonstrate that the interfacial interactions effectively reinforce dielectric polarization responses. Additionally, stable thermal infrared stealth ability and excellent mechanical strength endow the MXene/CoS aerogel with multifunctional properties. This work provides a general approach for the rational design of MXene/TMS aerogels with multifunctional applications and presents a new insight into the electromagnetic dissipation mechanism of interfacial bonds for boosting dielectric interactions.