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.

Two-dimensional (2D) materials have attracted extensive attention from aerospace, integrated circuits, precision sensors, and flexible electronics due to their unique layered structure and excellent physicochemical properties. In practice applications, the components of functional nanodevices are subjected to mechanical stress, which can affect the robust performance and structural reliability of these devices. Therefore, it is imperative to explore the mechanical properties and underlying mechanisms of 2D materials. However, researchers have an inadequate understanding of the accuracy of various in situ microscopy techniques and neglect the significance of high-quality, clean transfer techniques, resulting in deviated measurement results. There is now an urgent need to develop guidelines that allow researchers to select appropriate material transfer techniques and mechanical testing strategies based on the specific properties of 2D materials. Furthermore, the mechanical mechanism of 2D materials lacks systematic and comprehensive studies, which hinders researchers from deeply understanding the relationship between the material structure and the device performance. This work reviews the latest progress in the mechanics of 2D materials, focusing on the challenges of various transfer techniques and in situ microscopy techniques in mechanical testing, and provides effective guidance for the formulation of experimental schemes for mechanical testing. In addition, we offer detailed mechanistic insights into the fracture behavior, geometric dimension effects, edge defects, and interlayer bonding effects of 2D materials. This work is expected to advance the field development of 2D material mechanics.