Electrical conductivity and electromagnetic interference shielding in Ti3C2Tx MXene with point defects: a first-principles study.

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.