AVS 63rd International Symposium & Exhibition
    Tribology Focus Topic Thursday Sessions
       Session TR+BI+SE+TF-ThA

Paper TR+BI+SE+TF-ThA9
Nanoscale Friction Properties of Water Intercalated Graphene on Mica and its Isotope Effects

Thursday, November 10, 2016, 5:00 pm, Room 101A

Session: Materials Tribology
Presenter: Hyunsoo Lee, Institute for Basic Science (IBS) & Korea Advanced Institute of Science and Technology (KAIST)
Authors: H. Lee, Institute for Basic Science (IBS) & Korea Advanced Institute of Science and Technology (KAIST)
J.-H. Ko, KAIST, Republic of Korea
J.S. Choi, Electronics and Telecommunications Research Institute, Republic of Korea
J.H. Hwang, IBS & KAIST, Republic of Korea
Y.-H. Kim, KAIST, Republic of Korea
M.B. Salmeron, Lawrence Berkeley National Laboratory (LBNL)
J.Y. Park, IBS & KAIST, Republic of Korea
Correspondent: Click to Email
We demonstrate that the frictional behavior of hydrophobic graphene on hydrophilic mica is affected by water intercalation after exposure to humid air using atomic force microscopy. The single- and multi-layer graphene were formed by mechanical exfoliation on freshly cleaved muscovite mica. The adsorption of the ice-like water layer between graphene and mica led to friction enhancement, as compared with a pristine graphene/mica sample, which is presumably due to additional frictional energy dissipation at the solid–liquid interface. Moreover, friction on the graphene increased as the number of stacking water layers increased. The magnitude of friction increase was, on the other hand, reduced as following increase of the number of covering graphene layer above intercalated water layer, and then the friction is eventually not distinguished from the multi-layer graphene stack excluded water adsorption. Using the first-principle density functional theory calculations we explain this unexpected behavior by the increased spectral range of vibration modes of graphene caused by water, particularly the low frequency flexural modes, and by the better overlap of the graphene vibration modes with the mica phonons, which favors a more efficient dissipation of the frictional energy. Additionally, we found that the intercalation of deuterium oxide (D2O) leads to the lower friction, compared to H2O intercalated graphene on mica. We attribute this isotope effect with to the low vibrational frequency of D2O adsorbate, which results in the low rate of frictional energy dissipation at the interface.