Hierarchical Coconut‐Like Rigid‐Soft Structured Polydopamine@ <scp> Co ₃ O ₄ </scp> / <scp> Ti ₃ C ₂ T _x </scp> / <scp>PTFE</scp> Composite for Electromagnetic Protection with High Environmental

Comprehensive Summary Combining magnetic materials with high dielectric MXene has been proven to be an effective method to construct superb electromagnetic protective materials as they can introduce interface polarization and collaborate dielectric‐magnetic loss mechanism. However, the application of such hybrid structure is constrained by the obvious instability of MXene at acidic, basic, and high‐temperature environments. Herein, inspired by the great advantage of unique “hard shell and soft core” protective structure of natural coconuts, polydopamine (PDA)@Co 3 O 4 /Ti 3 C 2 T x (M)/polytetrafluoroethylene (PTFE) composite was fabricated for durable electromagnetic protective application. In this structure, the antioxidant PDA and chemically inert PTFE serve as a robust protective layer analogous to a “coconut shell”, effectively encapsulating the Co 3 O 4 /Ti 3 C 2 T x core, which functions as the primary additive for electromagnetic wave attenuation. The PDA@Co 3 O 4 /M/PTFE composite demonstrates a reflection loss (RL) value of −59.12 dB and an effective absorption bandwidth (EAB) of 6.72 GHz. It also exhibits electromagnetic shielding effectiveness of up to 27.67 dB and an absorption efficiency of 94.12%. Furthermore, the composite shows excellent environmental stability under acidic, basic, and sunlight exposure conditions, along with outstanding hydrophobic and flame‐retardant properties. In conclusion, the PDA@Co 3 O 4 /M/PTFE has significant potential to satisfy electromagnetic protective need of electronic systems, aerospace, and defense industries under harsh conditions.