Although speculation at this point, we anticipate that the amount of leakage into interfacial water might correlate with the tendency of an electrode to chemisorb water as suggested by the predominance of local density of states at the Fermi level on chemisorbed molecules . The existence of excess electrons within interfacial water might influence the energetics of interfacial ions affecting their detailed distribution at PZC and biased conditions. Such an effect could potentially explain the non-trivial slopes in Parsons-Zobel plots which exhibit increasingly non-ideal behavior in the order Au(111) < Pt(111) (see Fig. in Ref. ). Future more detailed work involving real ions will be necessary to test an according hypothesis.