Spatially Confined MXene Core‐Sheath Fibers for Switchable Broadband Microwave Absorption and Terahertz/Infrared Protection

ABSTRACT Integrating multispectral stealth with environmental robustness, while maintaining material flexibility, continues to pose a challenge in wearable electromagnetic materials. The orderly assembly of nanoscale electromagnetic units into hierarchically structured fibers imparts vitality to such systems. Herein, a dual‐spatially confined wet‐spinning strategy was proposed to fabricate MXene@Co 3 O 4 (M@C) core‐sheath fibers, selecting aramid nanofiber as the fiber substrate. The synergistic alignment and densification of MXene nanosheets create continuous conductive networks and a built‐in electric field in the core layer, facilitating efficient charge migration and interfacial accumulation for enhanced dielectric loss. Simultaneously, the sheath layer serves as a physical barrier to inhibit MXene oxidation while precisely modulating impedance matching. The resulting M@C fibers demonstrate exceptional mechanical strength and reliability under harsh conditions. The independent regulation across layers enables M@C fibers to achieve a remarkable minimum reflection loss of −55.32 dB and an ultra‐wide effective absorption bandwidth of 6.07 GHz at 2.60 mm. More importantly, the fibers enable orientation‐driven switchable responses originating from anisotropic charge transport and polarization behavior, while the woven fabric realizes multispectral absorption spanning X, Ku, K, and Ka bands, and provides terahertz/infrared protection. This work successfully integrates structural design with independent component optimization, providing a versatile platform for next‐generation wearable electromagnetic devices.