Abstract: Two-dimensional MXenes are well-known for their flexible intralayer/interlayer cooperative electron behavior. MXenes hold great potential for tailoring target properties through surface functionalization modification, such as optimized electromagnetic wave absorption (EWA). However, the regulation of dielectric loss and EWA performance via the anionic activation engineering of the MXene surface layer remains semi-empirical. Herein, the band structures and electron motions of two types of MXenes (Ti₃C₂ and Ti₂C) influenced by electronegative anions (O, S, and N) are designed and predicted. Based on first-principle calculations, two series of derivatives with surface-functionalized MXenes are prepared via the hydrothermal method and high-temperature sintering method, totaling eight groups of samples. The results show that the adsorption of anions at the edge active sites leads to the enrichment of internal electrons of the material at the edges and adjusts the intra/inter-layer charge transfer behavior, thus changing the dielectric properties. According to the ranking of intrinsic electronegativity, the conductance loss and polarization loss are self-tuning, enhancing the absorption of electromagnetic energy. In particular, the N-modified MXene can leverage interfacial polarization loss to achieve a remarkable enhancement in EWA performance, thereby effectively reducing the radar cross-section. In conclusion, this study can serve as a case of deductive scientific research work, providing ideas for the design of novel electromagnetic functional materials.

Key words: MXene, Two-dimensional materials, Dielectric properties, Electromagnetic wave absorption