Architecting Hierarchical Porous MXene/CoNi@CNT Hybrids for High-Performance Microwave Absorption via Synergistic Dielectric–Magnetic Regulation

The development of high-performance and lightweight microwave absorption materials (MAMs) requires effective strategies such as constructing multicomponent hetero interfaces and integrating multiple loss mechanisms. In this study, a series of magnetic CoNi@CNT nanoparticles were synthesized via a solvothermal method followed by thermal treatment, with the metal source ratio (Co/Ni) systematically adjusted to optimize their microstructure and electromagnetic wave absorption properties. The sample with a Co/Ni molar ratio of 1:1 was identified as the optimal magnetic component. Furthermore, porous MXene (PMXene) was employed as a dielectric substrate and combined with Co1Ni1@CNT through electrostatic self-assembly to form a hierarchical PMXene/CoNi@CNT hetero structure with synergistic dielectric–magnetic properties. This architecture not only enhanced interfacial polarization through multicomponent heterointerfaces but also improved impedance matching and attenuation capability via magnetic loss from CoNi alloys and extended conductive networks from CNT/PMXene. As a result, the composite with a dielectric-to-magnetic ratio of 1:1 at a low filler loading of 8 wt % exhibited a minimum reflection loss (RLmin) of −50 dB and an effective absorption bandwidth (EAB) of 4.3 GHz at a thickness of 1.5 mm, significantly outperforming pure PMXene (RLmin = −35 dB, EAB = 1.9 GHz). This work demonstrates the synergistic advantages of integrating MOF-derived magnetic components with two-dimensional dielectric substrates for high-efficiency microwave absorption, providing new insights into the design of advanced, lightweight electromagnetic functional materials.