Biomimetic Leaf‐Vein Aerogel for Electromagnetic Wave Absorption and Thermal Superinsulation

Abstract Electromagnetic protection in extreme environments requires materials with excellent thermal insulation capability and mechanical property to withstand severe temperature fluctuations and complex external stresses. Achieving strong electromagnetic wave absorption (EMA) while sustaining these exceptional properties remains a significant challenge. Herein, a facile approach is demonstrated to fabricate a biomimetic leaf‐vein MXene/CNTs/PI (MCP) aerogel with parallel venations through bidirectional freeze‐casting method. Due to its multi‐arch lamellar structure and parallel venations within the aerogel layers, the ultralight MCP aerogel (16.9 mg·cm −3 ) achieves a minimum reflection loss (RL min ) of −75.8 dB and a maximum effective absorption bandwidth (EAB max ) of 7.14 GHz with an absorber content of only 2.4 wt%, which also exhibits superelasticity and structural stability over a wide temperature range from −196 to 400 °C. Moreover, this unique structure facilitates rapid heat dissipation within the layers, while significantly impeding heat transfer between adjacent layers, achieving an ultralow thermal conductivity of 15.3 mW·m −1 ·K −1 for thermal superinsulation. The combination of excellent EMA performance, robust structural stability, and thermal superinsulation provides a potential design scheme under extreme conditions, especially in aerospace applications.