title: Robust ultra-low-friction state of graphene via moiré superlattice confinement.
abstract: 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.
authors.affiliation: 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.
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Gao
authors.affiliation: AML, CNMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Quanzhou
authors.initials: Q
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.|AML, CNMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Qunyang
authors.initials: Q
authors.lastname: Li
authors.affiliation: 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.
authors.forename: Miao
authors.initials: M
authors.lastname: Zhang
authors.affiliation: 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.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Xie
authors.affiliation: 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.
authors.forename: Shan
authors.initials: S
authors.lastname: Qiao
authors.affiliation: 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.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
authors.forename: Tianbao
authors.initials: T
authors.lastname: Ma
authors.affiliation: 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.
authors.forename: Zengfeng
authors.initials: Z
authors.lastname: Di
authors.affiliation: State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
authors.forename: Jianbin
authors.initials: J
authors.lastname: Luo
authors.affiliation: 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.
authors.forename: Xi
authors.initials: X
authors.lastname: Wang