Abstract: The discovery of tunable electronic and optical properties in two-dimensional (2D) materials has positioned strain engineering as a powerful tool for tailoring material functionalities. While much effort has been made to understand electronic and optical modulation under strain, mechanical reliability and fracture mechanisms remain critical for practical applications. In this study, we investigate the mechanical and electronic responses of Ti₂CX₂/WS₂ (X = O, F, OH) van der Waals heterostructures under uniaxial tensile deformation using density functional theory (DFT). The structural stability of the Ti₂CX₂/WS₂ heterostructures (X = O, F, OH) was validated by minimal lattice mismatch and confirmed through binding energy and phonon dispersion calculations. Stress-strain analyses revealed distinct mechanical responses compared to individual monolayers, with all heterostructures exhibiting enhanced ultimate tensile strength. Radial distribution function analysis confirmed that the fracture initiates from monolayer bond breaking. Hybrid functional calculations showed that only Ti₂CO₂/WS₂ maintained a strain-tunable bandgap, unlike the metallic behavior in Ti₂CF₂/WS₂ and Ti₂C(OH)₂/WS₂. Moreover, strain-induced transitions from type-II to type-I band alignment were observed, highlighting tunable interfacial electronic properties. These findings provide insight into designing robust and tunable 2D heterostructures for flexible and strain-engineered device applications.

Key words: MXene, Transition metal dichalcogenide (TMD), Heterostructure, Density functional theory, Strain engineering