State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China.
State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
Nat Commun. 2016 Oct 19;7:13204. doi: 10.1038/ncomms13204.
Two-dimensional (2D) materials possess outstanding lubrication property with their thicknesses down to a few atomic layers, but they are easily susceptible to sliding induced degradation or ubiquitous chemical modification. Maintaining the superior lubricating performance of 2D materials in a harsh working environment is highly desirable yet grandly challenging. Here we show that by proper alignment of graphene on a Ge(111) substrate, friction of graphene could be well preserved at an ultra-low level even after fluorination or oxidation. This behaviour is experimentally found to be closely related to the suppression of molecular-level deformation of graphene within the moiré superlattice structure. Atomistic simulations reveal that the formation of an interconnected meshwork with enhanced interfacial charge density imposes a strong anchoring effect on graphene even under chemical modification. Modulating molecular-level deformation by interfacial confinements may offer a unique strategy for tuning the mechanical or even chemical properties of 2D materials.
二维（2D）材料的厚度达到几个原子层时，具有出色的润滑性能，但它们很容易受到滑动诱导的降解或普遍的化学修饰的影响。在恶劣的工作环境中保持 2D 材料的卓越润滑性能是非常需要的，但也是极具挑战性的。在这里，我们展示了通过在 Ge(111)衬底上适当排列石墨烯，可以在氟化或氧化后很好地保持石墨烯的低摩擦性能。实验发现，这种行为与在莫尔超晶格结构内抑制石墨烯的分子级变形密切相关。原子模拟表明，形成具有增强的界面电荷密度的相互连接的网格结构对石墨烯施加了很强的锚固效应，即使在化学修饰下也是如此。通过界面约束来调节分子级变形可能为调节二维材料的机械甚至化学性质提供了一种独特的策略。
