Coupling Atomic‐Level Defect Engineering With Meta‐Structure Design in Ordered Mesoporous Carbon for Ultra‐Broadband Microwave Absorption

ABSTRACT Achieving scalable dielectric absorbers with ultra‐broadband performance remains challenging due to the intrinsic trade‐off between dielectric attenuation and impedance matching. Here, we report oxygen‐doped and vacancy‐engineered ordered mesoporous carbon (OOMC) prepared via a facile and scalable thermal oxidation strategy using commercially available polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene as the precursor. The ordered mesoporous structure enables uniform oxygen incorporation and vacancy formation, while moderate oxidation optimizes the dopant–defect balance, generating strong dipolar polarization. As a result, OOMC achieves an effective absorption bandwidth (EAB) of up to 6.9 GHz at 20 wt.% filler loading, significantly extending the bandwidth limit of conventional dielectric absorbers. Density functional theory calculations reveal that the synergistic coupling between oxygen dopants and vacancy defects induces localized charge redistribution and dipole polarization, enhancing dielectric attenuation at the atomic level. Integrating OOMC into a truncated‐pyramid meta‐structure further broadens the experimental EAB to 14.1 GHz with excellent angular stability. CST simulations confirm that this broadband enhancement originates from the cooperative effects of gradient impedance transition, multiple reflections, resonance coupling, and edge diffraction. This work establishes a scalable dual‐level design framework that couples atomic‐level defect–dopant engineering with structural metamaterial design, offering a pathway to break intrinsic bandwidth limitations in dielectric absorbers.