Mengxiang Liu, Kaifu Yang, Jiale Fan, Kaibo Yu, Zihan Kong, Tao Zhang, Xiaoxiao Huang
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 (RLmin) of -62.76 dB at a thickness of 2.43 mm and a maximum effective absorption bandwidth (EABmax) of 5.12 GHz at only 1.88 mm. The corresponding specific reflection loss values (SRLl and SRLlt) 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.