Reversible Electromagnetic Regime Transition in Defect-Programmed Carbon Textiles Toward Ultrabroadband Microwave Absorption.

Carbon textiles are attractive for lightweight electromagnetic protection but typically suffer from fixed functionality governed by intrinsic material properties. Here, we report a defect-programmed carbon textile that enables thermally reconstructed modulation of electromagnetic response through electronic-structure regulation. Sulfonation-induced crosslinking followed by carbonization establishes a conductive sp2 network exhibiting high electromagnetic interference (EMI) shielding effectiveness (∼43 dB) dominated by reflection, while subsequent thermal oxidation disrupts long-range electronic connectivity and introduces defect-mediated polarization, transforming the system into a microwave-absorbing regime. The electromagnetic response is governed by a conductivity-window effect, in which an optimal balance between impedance matching and intrinsic dissipation enables efficient microwave absorption. This balance leads to a non-monotonic evolution of absorption performance, with a maximum effective absorption bandwidth of 6.9 GHz achieved at intermediate oxidation. Importantly, the electromagnetic functionality can be repeatedly reconstructed through sequential ex situ thermal treatments, enabling switching between EMI shielding and microwave absorption regimes. Furthermore, the textile form enables direct integration into multilayer architectures, and CST simulations predict that structural amplification can extend absorption to 2-18 GHz. This work establishes a strategy for regulating electromagnetic response in continuous conductive networks and provides a textile-based platform for coupling electronic reconstruction with structural design toward broadband microwave absorption.