Al₂O₃-mediated heterogeneous interface engineering in MXene-derived TiO₂/N-doped carbon composites for synergistic...

Developing lightweight multifunctional materials that integrate efficient microwave absorption and thermal insulation remains a significant challenge for advanced electromagnetic protection applications. Herein, Al₂O₃-mediated MXene-derived TiO₂/N-doped carbon composites (AMNC) were engineered via a facile freeze-drying/thermal treatment strategy. During fabrication, in situ generated Al₂O₃ nanorods established abundant heterogeneous interfaces with MXene-derived TiO₂ and the N-doped carbon framework, constructing a hierarchical interface architecture that effectively regulated dielectric behavior. The synergistic effects of enhanced interfacial polarization, optimized conductive networks, and improved impedance matching endowed the AMNC composites with superior electromagnetic wave attenuation capability. The optimized AMNC-1 achieved a minimum reflection loss (RL_min) of -62.76 dB at a thickness of 2.43 mm and a maximum effective absorption bandwidth (EAB_max) of 5.12 GHz at only 1.88 mm. The corresponding specific reflection loss values (SRL_l and SRL_lt) reached 313.80 and 129.14, respectively, demonstrating excellent lightweight microwave absorption capability. Furthermore, CST simulations revealed a radar cross-section reduction of 34.62 dB m² under normal incidence, indicating promising radar stealth capability. Owing to the interconnected porous structure and Al₂O₃-mediated heterogeneous interface architecture, AMNC-1 exhibited excellent thermal insulation performance, maintaining a surface temperature of only 51.5 °C after heating on a 100 °C hot plate for 30 min. This work highlights the critical role of Al₂O₃-mediated heterogeneous interfaces in tailoring dielectric response and thermal insulation behavior, providing a rational strategy for designing lightweight multifunctional composites with synergistic electromagnetic absorption and thermal insulation performance.