▎ 摘　　要

Understanding molecular-scale friction at a liquid-solid interface in a nanofluidic system is essential, as friction affects slip behavior and flow properties at the nanoscale. In this research, we compute the molecular-scale friction at a water-graphene interface, combined with theoretical analysis and Molecular Dynamics (MD) simulation. A solid-solid friction model is modified, regarding a new method to calculate the work done by the substrate. The reliability of the computations is validated by MD results. It is manifested that liquid-solid friction, solid-solid friction, and viscous friction within liquids have similar mechanisms in terms of energy barriers. Moreover, we analyze the relationship between the slip behavior and the friction process and obtain a theoretical foundation between the slip velocity and the friction force based on a classic molecular kinetic theory. This foundation indicates a hyperbolic-like relation between the friction force and the slip velocity for a single water molecule, which is almost linear under realistic experimental conditions. This foundation provides a new way to determine the boundary condition for water flow between graphene sheets. Published under license by AIP Publishing.