Surface-termination control of nonlinear dynamics in functionalized 2D NEMS.

Surface functionalization provides an important route for tuning the properties of two-dimensional (2D) materials, yet its implications for nonlinear nanomechanical behavior remain insufficiently understood. Here, we examine how surface termination may influence the mechanical and nonlinear response of functionalized 2D nanoelectromechanical systems (NEMS), with emphasis on MXenes and comparison with graphene oxide and MoS₂. By combining literature-derived structural and elastic data with a reduced-order nonlinear resonator framework, we examine the roles of termination-dependent bonding, stiffness, electrostatic tuning, and parametric excitation. The analysis indicates that surface termination can modify the local bonding environment and thereby influence the effective mechanical response of MXene resonators. Cross-material and termination-dependent comparisons are presented as qualitative trends rather than as a universal quantitative relationship between bond length, stiffness, and nonlinearity. The resulting framework provides a physically motivated basis for relating surface chemistry to resonance behavior and for developing termination-by-design strategies for functionalized 2D NEMS. These results highlight surface termination as a potentially useful material-level design parameter for controlling the mechanical response and functionality of nanoscale resonators.