Adaptive Photothermal Superhydrophobic Modular Unit for Anti‐/De‐Icing Electromagnetic Window

Abstract Aircraft operating at high altitudes face demands for anti‐/de‐icing and electromagnetic compatibility. Photothermal superhydrophobic surfaces offer an energy‐efficient solution due to their rapid water removal, icing delay, and photothermal de‐icing. However, their strong reflectivity often fails to satisfy the strict electromagnetic requirements. Herein, an adaptive frequency selective surface (FSS) is designed using photothermal superhydrophobic modular units in a patterned array as an anti‐/de‐icing electromagnetic window, customizable for electromagnetic wave transmission or absorption to enable both radar stealth and photothermal regulation. A geometry‐electromagnetics co‐design based on equal‐area patterning further optimizes the trade‐off between photothermal fill factor and broadband microwave transparency. The modular unit employs Co 3 O 4 nanoneedles for efficient tip‐localized solar heating and alkylthiol passivation for durable superhydrophobicity. Accordingly, the optimized module achieves a prolonged icing delay of 1328 s and rapid photothermal de‐icing within 30 s under 1‐sun illumination, while maintaining over 90% radar transmittance across the 2–18 GHz range. This integrated and scalable solution combines advanced thermal management and radar stealth, offering a robust approach to aerospace surface protection.