After preparing the preliminary hydrated GO models (as described above), the procedure is quite similar to that of the anhydrous GO structures. To be specific, geometry and cell relaxation simulations were performed to relax the water molecules and to ensure their proper chemical configuration relative to the GO functional groups. In contrast to the anhydrous GO case, in the hydrated GO cell relaxation, we applied constraints on the a and b cell vectors to keep the GO structures preserved in the 2D plane and only the c vector was allowed to change. Afterwards, two stages of water equilibration were carried out. Namely, a 1 ps trajectory was generated using massive CSVR thermostats (with a time constant of 10 fs) followed by a 5 ps trajectory using global equilibration (with a time constant of 100 fs). Finally, a 30 ps production trajectory has been produced for each hydrated GO system using the same conditions that described above for the anhydrous systems.