The structure of the electrochemical double layer: Ag(111) in alkaline electrolyte

The structure of the electrochemical double layer at the interface between a Ag(111) electrode and 0.1 M KOH electrolyte has been probed using in-situ surface X-ray scattering (SXS). Detailed modeling of the SXS data at negative potential (E = − 1.0 V versus SCE) is consistent with the presence of an hydrated K+ cation layer at a distance of 4.1 ± 0.3 Å from the Ag surface and at positive potential (E = − 0.2 V), indicates that the presence of OHad stabilizes the hydrated K+ cations through a non-covalent interaction forming a compact double layer structure in which the Ag-K+ distance is reduced to 3.6 ± 0.2 Å.

► Surface X-ray diffraction study of the electrochemical interface between a Ag(111) electrode and alkaline electrolyte.
► Potential-dependent ordering of hydrated cations in the electrolyte side of the interface.
► Ordering due to a non-covalent OHad-hydrated cation interaction forming a compact electrolyte layer at the interface.