Since we will apply periodic boundary conditions (PBC) in all directions (see section 2.2), we added water above and below the double GO layer to ensure that the taking into account the images of the main cell there is always the same amount of confined water. The number of layers that we refer to when we discuss our models is the number of water layers that is confined between the two GO sheets, while the actual amount of water in the simulation cell equals twice that number. The different models are shown in Figure .