Tunable macroscale structural superlubricity in two-layer graphene via strain engineering

Abstract

Achieving structural superlubricity in graphitic samples of macro-scale size is particularly challenging due to difficulties in sliding large contact areas of commensurate stacking domains.Here, we show the presence of macro-scale structural superlubricity between two randomly stacked graphene layers produced by both mechanical exfoliation and CVD. By measuring the shifts of Raman peaks under strain we estimate the values of frictional interlayer shear stress (ILSS) in the superlubricity regime (mm scale) under ambient conditions. The random incommensurate stacking, the presence of wrinkles and the mismatch in the lattice constant between two graphene layers induced by the tensile strain differential are considered responsible for the facile shearing at the macroscale. Furthermore, molecular dynamic simulations show that the stick-slip behaviour does not hold for achiral shearing directions for which the ILSS decreases substantially, supporting the experimental observations. Our results pave the way for overcoming several limitations in achieving macroscale superlubricity in graphene.

Testing new graphene oxide‐coated glazing for papyrus manuscripts in museums: Part I

“…Over the years, glass in museum showcases has evolved from plain glass to ultra‐smooth, ultra‐clear, colorless, UV‐resistant, avoid flexing, chemically inert, lightweight, shatter‐resistant, scratch‐resistant, crack‐resistant, antifog, anti‐corrosion, and compact‐laminated glass that provides optimal protection and showcases valuable artifacts 14–16 . Discovered in the 21st century, graphene allowed new applications in different fields and showed outstanding thermal, optical, and electrical properties 17–19 . Graphene oxide (GO) coating has been used in touch screens of electronic devices and solar cells 20,21 and tested as a protective layer against the corrosion of industrial materials, including glass and metals 22–24 .…”

Macroscale robust superlubricity on metallic NbB2

“…Recent years have seen the emergence and development of a distinct class of materials operating in a remarkable regime of motion known as superlubricity (SL), which is de ned by nearly friction-free (friction coe cient less than 0.01) states of motion 1 . Major efforts in SL research have focused on materials like graphite [2][3][4] , graphene [5][6][7] , hexagonal BN 8,9 and MoS 2 [10][11][12][13] that possess strong intralayer bonding but very weak interlayer interactions, allowing easy sliding motion with small friction, which is further diminished via specially tailored incommensurate interlayer structural alignments. Such so-called structural SL is most viable at nano-to micro-scale where interlayer stacking can be effectively controlled.…”

Atomic-scale defects restricting structural superlubricity: Ab initio study study on the example of the twisted graphene bilayer

“…Twisted graphene bilayer has attracted recently considerable attention due to its unique electronic properties such as the possibility to observe superconductivity 1 and formation of a network of domain walls 2 with topologically protected helical states. 3,4 Relative rotation of graphene layers also gives rise to promising tribological properties, [5][6][7][8][9] namely structural superlubricity, i.e. the mode of relative motion of the layers with vanishing or nearly vanishing friction.…”

“…[12][13][14][15][16] Rotation of graphene layers to incommensurate superlubric orientations is responsible for such phenomena as self-retraction of graphene layers 8,9,17,18 and anomalous fast diffusion of a graphene flake on a graphite surface. 19,20 It should be mentioned that the phenomenon of structural superlubricity is observed not only for graphenebased systems [5][6][7][8][9] but also for multiwalled carbon nanotubes, 21 graphene nanoribbons on gold surfaces, 22 graphene/hexagonal boron nitride heterostructure, 23 etc. (see review 24 for more examples).…”