Optimizing the Electromagnetic Wave Absorption Performance of MXene@Sm(OH) ₃ Across the Ku Band Based on Asynchronous Permittivity Regulation

ABSTRACT The central challenge in the development of high‐performance electromagnetic wave‐absorbing materials lies in achieving an optimal balance between impedance matching and attenuation characteristics. This is particularly critical for purely dielectric absorbers, where precise tailoring of the real ( ε ′) and imaginary ( ε ″) parts of the complex permittivity is essential for maximizing energy dissipation while minimizing surface reflection. In this work, we propose an innovative asynchronous regulation strategy through the construction of Ti 3 C 2 T x /Sm(OH) 3 heterointerfaces with complementary dielectric properties. This approach enables independent tuning of dielectric parameters to decouple and synergistically optimize impedance matching and loss capability. Results demonstrate that the optimized Ti 3 C 2 T x /Sm(OH) 3 composite with a mass ratio of 4:1 exhibits exceptional microwave absorption performance. A minimum reflection loss (RL min ) of −54 dB is achieved at 14.6 GHz, along with an ultrawide effective absorption bandwidth (EAB) of 7 GHz (13–20 GHz), at a minimal thickness of only 1.70 mm. The rod‐like morphology of Sm(OH) 3 mitigates excessive interfacial polarization loss caused by redundant heterogeneous interfaces, contributing to a more efficient and balanced attenuation mechanism. Our findings underscore asynchronous permittivity regulation as an effective and innovative strategy for designing advanced electromagnetic wave absorbers with customized performance metrics.