Arvelo Diana M, Uhlig Manuel R, Comer Jeffrey, García Ricardo
Instituto de Ciencia de Materiales de Madrid, CSIC, c/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
Nanotechnology Innovation Center of Kansas State, Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas, 66506, USA.
Nanoscale. 2022 Oct 6;14(38):14178-14184. doi: 10.1039/d2nr04161h.
Interfacial water participates in a wide range of phenomena involving graphite, graphite-like and 2D material interfaces. Recently, several high-spatial resolution experiments have questioned the existence of hydration layers on graphite, graphite-like and 2D material surfaces. Here, 3D AFM was applied to follow in real-time and with atomic-scale depth resolution the evolution of graphite-water interfaces. Pristine graphite surfaces upon immersion in water showed the presence of several hydration layers separated by a distance of 0.3 nm. Those layers were short-lived. After several minutes, the interlayer distance increased to 0.45 nm. At longer immersion times (∼50 min) we observed the formation of a third layer. An interlayer distance of 0.45 nm characterizes the layering of predominantly alkane-like hydrocarbons. Molecular dynamics calculations supported the experimental observations. The replacement of water molecules by hydrocarbons on graphite is spontaneous. It happens whenever the graphite-water volume is exposed to air.
界面水参与了涉及石墨、类石墨和二维材料界面的广泛现象。最近，一些高空间分辨率实验对石墨、类石墨和二维材料表面水化层的存在提出了质疑。在此，应用三维原子力显微镜实时跟踪并以原子尺度深度分辨率研究石墨-水界面的演变。原始石墨表面浸入水中时显示存在几个水化层，层间距为0.3纳米。这些层寿命短暂。几分钟后，层间距增加到0.45纳米。在更长的浸入时间（约50分钟）后，我们观察到第三层的形成。0.45纳米的层间距表征了主要为类烷烃的分层情况。分子动力学计算支持了实验观察结果。石墨上的水分子被烃类取代是自发的。只要石墨-水体系暴露在空气中就会发生这种情况。
