Melanin-like nanofibers with highly ordered structures achieve unprecedented specific electromagnetic interference shielding efficiency

Lightweight, high-performance electromagnetic shielding materials are crucial for protection and detection, relying heavily on the precise design of electromagnetic response structures. Conventional shielding materials often involve complex fabrication of conjugated composites or graphitization of organic materials, facing challenges in balancing their performance and processability. As such, seeking intrinsically conjugated materials with superior processability is crucial. Natural melanin and melanin-like polymers have garnered considerable attention as emerging promising energy-dissipating substances with a wide range from ionizing radiation to infrared light. In this work, we have engineered those bioinspired polymers with highly ordered microstructures as a new class of promising high-performance and lightweight electromagnetic shielding materials for the first time. The key process is to use 5, 6-dihydroxyindole ring tetramer framework to construct highly ordered melanin-like nanofibers by tuning the intramolecular π-π stacking, which could facilitate the well regulation of long-range electron conduction and electromagnetic matching features. The resulting melanin-like nanofibers could be easily transformed into carbon aerogels with outstanding microwave absorption performance, i.e. a maximum reflection loss of -68.87dB and effective absorption bandwidth of 5.25GHz during 2-18GHz. In the X-band, the aerogel reached the considerable absolute EMI shielding effectiveness value of 47909.9 dB cm ² /g, the highest for organic carbon materials reported to date. This work represented the first successful extension of the electromagnetic response of melanin-like polymers into the microwave spectrum, paving the way for practical applications of bioinspired polymers in EMI shielding and stealth technologies.