Robust interlayer superlubricity of graphene enabled by water intercalation

Structural superlubricity can be achieved at incommensurate sliding between graphene layers. However, this superlubricity readily fails due to the transition of incommensurate-commensurate contact for energetically favorable interlayer slidings. This work proposes a novel strategy to sustain robust interlayer superlubricity by intercalating water films between graphene layers. It is found that the rate of frictional energy dissipation during the interlayer sliding is significantly reduced by ~5 times in the presence of water intercalation. Such reduction originates from the isotropic ultra-low friction characteristic of graphene-water interface, which prevents the graphene interlayer from locking at energetically favorable commensurate sliding. Molecular dynamics simulations reveal that the structural misalignment between graphene carbon atoms and water oxygen atoms contributes to the friction isotropy of graphene-water interface, while its ultra-low friction behavior results from the low surface energy and the atomically smooth surface of the intercalated water film. These observations offer valuable insights for promoting the superlubricity applications of graphene-based materials through the design of solid-liquid sliding interfaces.