We report an investigation of the friction mechanisms of MoS₂ thin films under changing environments and contact conditions using a variety of computational and experimental techniques. Molecular dynamics simulations were used to study the effects of water and molecular oxygen on friction and bonding of MoS₂ lamellae during initial sliding. Characterization via photoelectron emission microscopy (PEEM) and Kelvin probe force microscopy (KPFM) were used to determine work function changes in shear modified material within the top few nanometers of MoS₂ wear scars. The work function was shown to change with contact conditions and environment, and shown by density functional theory (DFT) calculations and literature reports to be correlated with lamellae size and thickness of the basally oriented surface layer. Results from nanoscale simulations and macroscale experiments suggest that the evolution of the friction behavior of MoS₂ is linked primarily to the formation or inhibition of a basally oriented, molecularly thin surface film with long-range order.

我们报告了使用各种计算和实验技术在不断变化的环境和接触条件下研究 MoS ₂薄膜的摩擦机制。分子动力学模拟被用来研究水和分子氧在初始滑动过程中对 MoS ₂薄片摩擦和结合的影响。使用光电子发射显微镜 (PEEM) 和开尔文探针力显微镜 (KPFM) 进行表征，以确定在 MoS ₂顶部几纳米范围内剪切改性材​​料的功函数变化穿伤疤。功函数显示出随着接触条件和环境而变化，并通过密度泛函理论 (DFT) 计算和文献报告显示与基底取向表面层的薄片尺寸和厚度相关。纳米尺度模拟和宏观尺度实验的结果表明，MoS ₂摩擦行为的演变主要与具有长程有序的基础取向的分子薄膜表面膜的形成或抑制有关。