A HB bridge is defined as a chain of GO-water (and, in some cases, water-water) intermolecular HBs that co-exist and extend from one GO sheet to the other. These bridges will be classified into different types based on the number of involved H 2 O molecules. Thereby, an n-th order bridge exists if there are n water molecules bridging the two GO layers. Although longer H-bonded chains may in principle exist, we will concentrate on the shortest possible bridge, which is of order n for OGOn and RGOn.