Design and Radar Stealth Performance of High-Efficiency Nb₂CT_<i>x</i>-MXene/α-Fe Heterogeneous Composites with Synergistic Magnetic-Dielectric Loss

In this study, inorganic Nb2CTx MXene was synthesized through a hydrofluoric acid etching process, and α-Fe nanoparticles prepared via the thermal decomposition of iron pentacarbonyl were combined in varying weight ratios through electrostatic self-assembly. Remarkably, α-Fe@6%Nb2CTx composite with a thickness of 1.5 mm, achieves highly efficient microwave absorption with an ultrawide effective absorption bandwidth (EAB) of 7.2 GHz, covering the frequency range of 10.8 to 18 GHz, representing more than a 100% increase in comparison to single-phase α-Fe, which has an EAB of 3.2 GHz. Further increases in Nb2CTx content, up to 20%, shift the EAB toward lower frequencies, approaching 2 GHz. The superior electromagnetic wave absorption performance of α-Fe@Nb2CTx composites results from the synergistic interplay of multicomponent interfacial polarization, diverse loss mechanisms, and optimized impedance matching, as validated by electromagnetic parameter analysis. Moreover, the synergistic magnetic and dielectric loss characteristics of Nb2CTx MXene outperform those of previously reported titanium and vanadium carbide MXenes, which possess only dielectric loss properties, making it a uniquely effective material for electromagnetic wave absorption. The exceptional capability of the α-Fe@Nb2CTx MXene composite to attenuate electromagnetic waves (EMWs) was validated by radar cross-section (RCS) computations, which achieved a maximum RCS reduction value of 36.4 dBsm at an incident wave angle of θ = 37.6°. This study presents advancements in the design and development of high-performance, multicomponent heterostructure composites as next-generation electromagnetic wave absorbers with wideband absorption, superior efficiency, lightweight properties, and ultrathin structures, making them highly promising for radar stealth applications.