Ultrahigh Lubricity between Two-Dimensional Ice and Two-Dimensional Atomic Layers

Low temperature and high humidity conditions significantly degrade the performance of solid-state lubricants consisting of van der Waals (vdW) atomic layers, owing to the liquid water layer attached/intercalated to the vdW layers, which greatly enhances the interlayer friction. However, using low temperature in situ atomic force microscopy (AFM) and friction force microscopy (FFM), we unveil the unexpected ultralow friction between two-dimensional (2D) ice, a solid phase of water confined to the 2D space, and the 2D molybdenum disulfides (MoS2). The friction of MoS2 and 2D ice is reduced by more than 30% as compared to bare MoS2 and the rigid surface. The phase transition of liquid water into 2D ice under mechanical compression has also been observed. These new findings can be applied as novel frictionless water/ice transport technology in nanofluidic systems and promising high performance lubricants for operating in low temperature and high humidity environments.

Automated summary

Low temperature and high humidity conditions degrade the performance of solid-state lubricants by enhancing interlayer friction due to the presence of liquid water layer attached to the van der Waals (vdW) atomic layers. However, this study reveals unexpected ultralow friction between 2D ice and 2D molybdenum disulfides (MoS2) using low temperature in situ atomic force microscopy (AFM) and friction force microscopy (FFM). The friction of MoS2 and 2D ice is reduced by more than 30% compared to bare MoS2 and rigid surface.