Ultrahigh elastic modulus and tensile strength of monolayer Mo₂TiC₂T_x MXene by dual transition metal bonding

Two-dimensional (2D) transition metal carbides or nitrides (MXenes) provide a versatile class of materials with tunable surface chemistry and distinctive mechanical and electronic functionalities. Among them, Mo₂TiC₂T_x, a representative dual transition metal MXene, is distinguished by its electrochemical activity and energy storage capability. Since the reliability of such devices is closely linked to the mechanical response of their smallest structural units, a clear understanding of the intrinsic mechanical properties and fracture behavior of monolayer Mo₂TiC₂T_x is required. Here, using a Push-to-Pull (PTP) device inside a scanning electron microscope (SEM), we directly measure a Young’s modulus of 563.09 ± 11.27 GPa for freestanding monolayer Mo₂TiC₂T_x, consistent with density functional theory (DFT) predictions for dual transition metal MXenes. DFT calculation further tracks bond-length evolution and charge-density redistribution during uniaxial tension, clarifying the microscopic origin of the exceptional stiffness and strength. This work elucidates the physical origin of the enhanced mechanical properties of bimetallic MXenes, demonstrates their potential in advanced energy and functional material systems, and provides key experimental and theoretical insights for improving structural reliability and failure prediction in other 2D materials.