Superlubric sliding of graphene nanoflakes on graphene.

The lubricating properties of graphite and graphene have been intensely studied by sliding a frictional force microscope tip against them to understand the origin of the observed low friction. In contrast, the relative motion of free graphene layers remains poorly understood. Here we report a study of the sliding behavior of graphene nanoflakes (GNFs) on a graphene surface. Using scanning tunneling microscopy, we found that the GNFs show facile translational and rotational motions between commensurate initial and final states at temperatures as low as 5 K. The motion is initiated by a tip-induced transition of the flakes from a commensurate to an incommensurate registry with the underlying graphene layer (the superlubric state), followed by rapid sliding until another commensurate position is reached. Counterintuitively, the average sliding distance of the flakes is larger at 5 K than at 77 K, indicating that thermal fluctuations are likely to trigger their transitions from superlubric back to commensurate ground states.

[1]  Joost W. M. Frenken,et al.  Model calculations of superlubricity of graphite , 2004 .

[2]  Xiaofeng Feng,et al.  Water splits epitaxial graphene and intercalates. , 2012, Journal of the American Chemical Society.

[3]  I. Vobornik,et al.  Two distinct phases of bilayer graphene films on Ru(0001). , 2012, ACS nano.

[4]  M. Salmeron,et al.  Scratching the Surface: Fundamental Investigations of Tribology with Atomic Force Microscopy. , 1997, Chemical reviews.

[5]  J. Frenken,et al.  Superlubricity of graphite. , 2004, Physical review letters.

[6]  S. Marchini,et al.  Scanning tunneling microscopy of graphene on Ru(0001) , 2007 .

[7]  Quanshui Zheng,et al.  Observation of microscale superlubricity in graphite. , 2012, Physical review letters.

[8]  Francesco Zerbetto,et al.  Synthetic molecular motors and mechanical machines. , 2007, Angewandte Chemie.

[9]  Scott S. Verbridge,et al.  Electromechanical Resonators from Graphene Sheets , 2007, Science.

[10]  Sheng Wang,et al.  Self-retracting motion of graphite microflakes. , 2007, Physical review letters.

[11]  Y. Qi,et al.  Surface Species Formed by the Adsorption and Dissociation of Water Molecules on a Ru(0001) Surface Containing a Small Coverage of Carbon Atoms Studied by Scanning Tunneling Microscopy , 2008 .

[12]  Francesco Bonaccorso,et al.  Brownian motion of graphene. , 2010, ACS nano.

[13]  A. Tkatchenko,et al.  Stacking and registry effects in layered materials: the case of hexagonal boron nitride. , 2010, Physical review letters.

[14]  G. McClelland,et al.  Atomic-scale friction of a tungsten tip on a graphite surface. , 1987, Physical review letters.

[15]  C. Durkan,et al.  Tailoring the local interaction between graphene layers in graphite at the atomic scale and above using scanning tunneling microscopy. , 2009, ACS nano.

[16]  T. Ma,et al.  Molecular dynamics simulation of the interlayer sliding behavior in few-layer graphene , 2012 .

[17]  Zettl,et al.  Low-friction nanoscale linear bearing realized from multiwall carbon nanotubes , 2000, Science.

[18]  Barriers to motion and rotation of graphene layers based on measurements of shear mode frequencies , 2012, 1205.0777.

[19]  N. Lorente,et al.  Graphene on Ru(0001): contact formation and chemical reactivity on the atomic scale. , 2010, Physical review letters.

[20]  A. Bostwick,et al.  Friction and dissipation in epitaxial graphene films. , 2009, Physical review letters.

[21]  Conductance fluctuations as a function of sliding motion in bilayer graphene nanoribbon junction: A first-principles investigation , 2012 .

[22]  M. Urbakh,et al.  Low friction and rotational dynamics of crystalline flakes in solid lubrication , 2011, 1108.2400.

[23]  O. Hod.  Interlayer commensurability and superlubricity in rigid layered materials , 2012 .

[24]  M. Hirano,et al.  Dynamics of friction: superlubric state , 1993 .

[25]  M. Hybertsen,et al.  Electronic structure of few-layer epitaxial graphene on Ru(0001). , 2009, Nano letters.

[26]  V. Crespi,et al.  Registry-dependent interlayer potential for graphitic systems , 2005 .

[27]  Y. Shibuta,et al.  Interaction between two graphene sheets with a turbostratic orientational relationship , 2011 .

[28]  E. Sutter,et al.  Scanning tunneling microscopy on epitaxial bilayer graphene on ruthenium (0001) , 2009 .

[29]  D Fleishman,et al.  Mesoscale engines by nonlinear friction. , 2007, Nano letters.

[30]  J. M. Martín,et al.  Superlubricity of molybdenum disulphide. , 1993, Physical review. B, Condensed matter.

[31]  R. Superfine,et al.  Nanometre-scale rolling and sliding of carbon nanotubes , 1999, Nature.

[32]  P. Depondt,et al.  Self-locking of a modulated single overlayer in a nanotribology simulation , 1998 .

[33]  Bin Wang,et al.  Interfacial coupling in rotational monolayer and bilayer graphene on Ru(0001) from first principles. , 2012, Nanoscale.

[34]  Chun Zhang,et al.  Adsorption of gas molecules on transition metal embedded graphene: a search for high-performance graphene-based catalysts and gas sensors , 2011, Nanotechnology.

[35]  A. Cervellino,et al.  Graphene on Ru(0001): a 25 x 25 supercell. , 2008, Physical Review Letters.

[36]  Changgu Lee,et al.  Frictional Characteristics of Atomically Thin Sheets , 2010, Science.

[37]  Commensurate-incommensurate phase transition in bilayer graphene , 2011, 1108.2254.

[38]  G. Galli,et al.  Nature and strength of interlayer binding in graphite. , 2009, Physical review letters.

[39]  B. Potapkin,et al.  Fast diffusion of a graphene flake on a graphene layer , 2010, 1102.4103.

[40]  J. Frenken,et al.  Model experiments of superlubricity of graphite , 2005 .

[41]  D. Ralph,et al.  Reactivity of monolayer chemical vapor deposited graphene imperfections studied using scanning electrochemical microscopy. , 2012, ACS nano.

[42]  Jong-Hyun Ahn,et al.  Chemical vapor deposition-grown graphene: the thinnest solid lubricant. , 2011, ACS nano.

[43]  R. Kaneko,et al.  Observation of Superlubricity by Scanning Tunneling Microscopy , 1997 .

[44]  Xiaofeng Feng,et al.  Electronic screening in stacked graphene flakes revealed by scanning tunneling microscopy , 2013 .

[45]  Joseph Klafter,et al.  Torque and twist against superlubricity. , 2008, Physical review letters.

[46]  A. Krasheninnikov,et al.  Structural defects in graphene. , 2011, ACS nano.