Constructing two-dimensional interfacial ice-like water at room temperature for nanotribology

Water/solid interfaces play crucial roles in a wide range of physicochemical and technological processes. However, our microscopic understanding of the interfacial water under ambient temperature is relatively primitive. Herein, we report the direct experimental construction of two-dimensional (2D) ice-like water layer on hydrophilic surface at room temperature by using environment-controlled atomic force microscopy. In contrast to the prevailing view that nanoscale confinement is needed for the formation of 2D ice-like water, we find that 2D ice-like water can form on mica surface at temperatures above the freezing point without confinement. The 2D ice-like water layer shows epitaxial relation with the underlying mica lattice and good thermostability. In addition, the growth of ice-like water layer can be well controlled by the mechanical force from the scanning tip. Furthermore, the friction properties of 2D ice-like water layer are also probed by friction force microscopy. It is found that the ice-like water layer can dramatically reduce the friction. These results provide deep understanding of 2D ice-like water formation on solid surfaces without nanoscale confinement and suggest means of growing 2D ices on surfaces at room temperature.