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Limited by the types of suitable absorbents as well as the challenges in engineering the nanostructures (e.g., defects, dipoles, and hetero‐interface) using state‐of‐the‐art additive manufacturing (AM) techniques, the electromagnetic (EM) wave absorption performance of the current ceramic‐based materials is still not satisfying. Moreover, because of the high residual porosity and the possible formation of cracks during sintering or pyrolysis, AM‐formed ceramic components may in many cases exhibit low mechanical strength. In this work, semiconductive MoS2 and conductive PyC modified Al2O3 (MoS2/PyC‐Al2O3) ceramic‐based structural EM metamaterials are developed by innovatively harnessing AM, precursor infiltration and pyrolysis (PIP), and hydrothermal methods. Three different meta‐structures are successfully created, and the ceramic‐based nanocomposite benefit from its optimization of EM parameters. Ultra‐broad effective absorption bandwidth (EAB) of 35 GHz is achieved by establishment of multi‐loss mechanism via nanostructure engineering and fabrication of meta‐structures via AM. Due to the strengthening by the PyC phase, the bending strength of the resulting ceramics can reach ≈327 MPa, which is the highest value measured on 3D‐printed ceramics of this type that has been reported so far. For the first time, the positive effect deriving from the engineering of the microscopic nano/microstructure and of the macroscopic meta‐structure of the absorber on the permittivity and EM absorption performance is proposed. Integration of outstanding mechanical strength and ultra‐broad EAB is innovatively realized through a multi‐scale design route. This work provides new insights for the design of advanced ceramic‐based metamaterials with outstanding performance under extreme environment.

The proliferation of electronic devices and wireless communication is leading to serious electromagnetic (EM) interference. In this work, Ti 3 C 2 /cement composites were developed as high efficiency EM functional materials by introducing exfoliated Ti 3 C 2 T x MXene with cement for green buildings with EM shielding function. In the composites, few-layered Ti 3 C 2 MXene were dispersed homogeneously throughout the cement matrix. The EM properties of the composites were studied as a function of the MXene content. With increasing MXene content, real and imaginary part of permittivity was significantly improved owing to the polarization and electrical conduction caused by the MXene phase. Composites with 15 wt.% MXene showed good EM absorbing properties with a maximum effective absorbing bandwidth of 2.67 GHz. Strong EM shielding can be achieved when MXene content increased to 25 wt.%. The EM shielding effectiveness of such composites was higher than 22.0 dB, and the dominating shielding mechanism was EM absorption. This work finds new materials for the development of advanced green buildings with EM shielding function.