Impedance Matching-Guided Multilayer Engineering in Magnetic MXene Composites for Ultra-Broadband Electromagnetic Wave Absorption.

The high-performance electromagnetic wave (EMW) absorbing materials face a fundamental challenge: traditional homogeneous absorbers struggle to achieve both broad bandwidth and strong absorption due to the limitations imposed by the Kramers-Kronig relations. To overcome this constraint, an impedance matching-guided multilayer engineering strategy is proposed to spatially decouple this trade-off via electromagnetic gradient architectures enabling ultra-broadband EMW absorption. To verify this strategy, magnetic Ni@MXene absorbents with tuneable electromagnetic ratios were synthesized via electrostatic self-assembly and in situ reduction, followed by shear-induced alignment to construct homogeneous laminated composites. While the single laminated composites deliver strong absorption (minimum reflection loss, RLmin of -62.21 dB) yet limited effective absorption bandwidth (EAB, 3.68 GHz). By assembling the laminated composites into the electromagnetic gradient multi-layered composite with optimized stacking sequence and layer thickness based on our impedance matching-guided multilayer engineering, a three-layer structure composite (G3) achieves an ultra-broad EAB of 10.4 GHz and a RLmin of -60.12 dB. This exceptional performance stems from synergistic impedance matching for wave penetration and cascade dissipation across the thickness direction. This work provides a design framework for broadband high-efficiency EMW absorbing materials with implications for next generation of electromagnetic stealth technology.