Lim Yeonsoo, Park Haiwoong, Caron Arnaud
KoreaTech - Korea University of Technology and Education Cheonan 31253 Republic of Korea
RSC Adv. 2019 Mar 4;9(13):7285-7291. doi: 10.1039/c8ra10584g. eCollection 2019 Mar 1.
We investigated the role of interfacial water on the atomic-scale tribology of graphite by contact atomic force microscopy. Upon the approach of Au and Pt tips toward graphite in water, the hydration layers on the respective surfaces interact with each other. This results in a discontinuous motion of the metallic tips towards the graphite surface. Snap-in forces measured with Au and Pt tips scale with their respective water adsorption energies. Moreover, we observed significant differences for the atomic-scale friction between the Au and Pt tips and graphite in water. The atomic-scale sliding friction between an Au tip and graphite is characterized by low friction forces ( < 1 nN in the range of normal force values = 1-10 nN) and by a periodic stick-slip that corresponds to the honeycomb structure of graphite. With a Pt tip, the sliding friction on graphite in water is characterized by high friction forces ( ≈ 5 nN in the range of normal force values = 1-10 nN) and by an atomic-scale stick-slip whose characteristic lengths may correspond to an ordered water adsorption layer between platinum and graphite.
我们通过接触原子力显微镜研究了界面水在石墨原子尺度摩擦学中的作用。当金和铂探针在水中靠近石墨时，各自表面的水化层相互作用。这导致金属探针向石墨表面的运动不连续。用金和铂探针测量的扣合力与其各自的水吸附能成比例。此外，我们观察到金和铂探针与水中石墨之间在原子尺度摩擦方面存在显著差异。金探针与石墨之间的原子尺度滑动摩擦的特点是摩擦力较低（在法向力值(F_n = 1 - 10) nN范围内(< 1) nN），且具有与石墨蜂窝结构相对应的周期性粘滑现象。使用铂探针时，水中石墨上的滑动摩擦的特点是摩擦力较高（在法向力值(F_n = 1 - 10) nN范围内(\approx 5) nN），且具有原子尺度的粘滑现象，其特征长度可能对应于铂和石墨之间的有序水吸附层。
