Electrical conductivity and electromagnetic interference shielding in Ti₃C₂T_x MXene with point defects: a...

MXenes, a rapidly expanding family of two-dimensional (2D) materials, hold great research interest for electromagnetic interference (EMI) shielding applications owing to their tunable surface chemistry and superior metallic conductivity. Here, using first-principles calculations, we investigate intrinsic vacancy defects in Ti₃C₂T₂ monolayers and their effects on electronic structure, electrical conductivity and estimated EMI shielding performance. Surface Ti and C vacancies are shown to introduce localized states and band flattening around the Fermi level, resulting in a decrease in electrical conductivity. Different surface terminations (-OH, -Cl, -F, and -S) significantly modulate the defect formation energy and electronic transport properties, with calculated conductivities ranging from 4401 S cm^-1 for Ti₃C₂O₂ to 13 686 S cm^-1 for Ti₃C₂S₂. The calculated conductivity values correspond to estimated EMI shielding effectiveness exceeding 53 dB, while vacancy defects can decrease effectiveness due to the introduction of scattering centers. However, defect properties vary with termination groups and can even maintain effectiveness in some cases, with zero conductivity decrease for the Ti vacancy in Ti₃C₂(OH)₂. This work provides atomic-level insight into how defects and surface terminations tune intrinsic electronic structure, conductivity and EMI shielding effectiveness, offering theoretical guidance for high-conductivity MXene films for EMI shielding applications.