First, we identified the aforementioned bridges using the geometric criteria given above and counted their occurrence in the corresponding trajectories. Figure displays histograms for the investigated bridges in relation to the number of possible donor-acceptor groups (pairs of functional groups on different GO layers close enough to be connected by an n-th order bridge). As can be seen in Figure , for the shortest inter-layer distance there is a clear difference between the OGO1 and RGO1 models. The weighted average (given in table 1) of the number of bridges/pair of functional groups in the random system RGO1 is 0.93, whereas it is 0.62 for OGO1. Increasing the amount of confined water (hence, the inter-layer distance) from one to two layers increases the probability of forming more HB bridges involving different water molecules. Indeed the number of 2nd order bridges in OGO2 increases by about 0.2 as compared to OGO1 (cf. the blue lines in Figure vs. 6b). In contrast, the number of 2nd order bridges in RGO2 increases only by about 0.01. In general both distributions are broader than in case of a single water layer. Figure shows that for 3rd order bridges the difference between the ordered and random systems essentially vanishes (difference is 0.01). Thus, we can conclude that: (1) the spatial arrangement of the GO functional groups has an insignificant effect on the number of the HB bridges as the distance between GO layers increases (> 12 Å), and (2) to have the maximum number of HB bridges, the optimum number of water layers is 1-2 for the random GO, and 2-3 for the ordered GO. To have a better understanding of the dependence of the H-bonded bridges on the different functional groups, we categorized them into six patterns based on the types of the two terminal HBs (donor and acceptor type according to Figure ). Figure displays snapshots of examples of these bridge patterns. The counts of these patterns in each system are given in Table . From the table one notices that, in all studied models, the OH don -OH acc bridge pattern (cf. Figure ) has by far the highest occurrence probability (cf. the highlighted row in Table ).