The metals absorbed on the graphene/GO structures were first relaxed using DFT through the Quickstep 36 module of CP2K, until forces were inferior to 1.0E-03 a.u. Later, ab-initio MD simulations, based on the propagation of the equations of motion with Langevin dynamics, were performed in the canonical ensemble at 310 K. The graphene/GO structures have been kept fixed, while water has been allowed to move freely. Each simulation ran for 4 ps, using a timestep of 1 fs. intercept is the extrapolated zero-velocity point. According to the physical definition, the slip length (𝑙 𝑠 ) is the distance from the channel wall to the extrapolated zero velocity point . If the water molecules move frictionless through the channel (Figure ), the zero-velocity plane is parallel to the real velocity plane, resulting in infinitive slip length (𝑙 𝑠 = ∞). Moreover, if the friction between water molecules and tunnel walls increased to maximum, the velocity of water molecules that are close to the tunnel walls approaches to zero (Figure ). The intercept point is located on the surface of the tunnel wall leading to a non-slip condition (𝑙 𝑠 = 0).