Enhanced impedance matching driven by interfacial polarization in Ti₃C₂Cl_x@CuCo₂S₄ MXene heterostructures for efficient electromagnetic wave absorption

MXene is a highly promising electromagnetic wave (EMW) absorption material. However, its high electrical conductivity often leads to impedance mismatch, limiting its EMW absorption capability. Herein, a synergistic regulation strategy relying on the optimization of dielectric loss and enhancement of built-in electric field respectively achieved by introduction of Cl terminals and flower-like CuCo₂S₄ microspheres into Ti₃C₂T _x MXene, thus regulating the EMW absorption capability of MXene. Cl can act as terminal group while flower-like CuCo₂S₄ microspheres will uniformly anchor on Ti₃C₂Cl _x , forming an interconnected three-dimensional heterogeneous network. Then, by tuning the Cu/Co ratio, the EMW absorption behavior of Ti₃C₂Cl _x @CuCo₂S₄ can be effectively modulated. Specifically, Ti₃C₂Cl _x @CuCo₂S₄-6 delivers an ultrawide effective absorption bandwidth of 7.64 GHz at a thickness of 3.10 mm, while Ti₃C₂Cl _x @CuCo₂S₄-8 achieves a minimum reflection loss of −60.41 dB. The enhanced absorption performance is primarily attributed to the optimized dielectric loss induced by surface termination regulation, together with the built-in electric field generated by interfacial charge transfer and the increased interfacial density, as revealed by density functional theory calculations. Moreover, radar cross-section simulations demonstrate the potential Ti₃C₂Cl _x @CuCo₂S₄ for radar stealth applications. This work provides a feasible and effective strategy for design of lightweight, high-performance MXene-based EMW absorbers.