Ex situ X-ray photoelectron spectroscopy study of the interface between a Ag(111) electrode and an alkaline electrolyte. 2. Structure of the double layer

A Ag(111) single-crystal electrode emersed from an alkaline NaF + NaOH elec trolyte under various potentials has been studied ex situ by means of X-ray photoelectron spectroscopy. Superequivalent specific adsorption of negativ ely charged hydroxide and oxide species has been observed at the potentials positive to the point of zero charge (E-pzc). The interfacial electroneutr ality is provided by the Coulombic attraction of Na+ cations, which are ret ained in the emersed double layer. Once the emersed electrode is heated in an ultrahigh vacuum above 370 K, the double layer disintegrates via the dec omposition of the adsorbed hydroxide and surface oxide species and likely d issolution of sodium in the Ag(111) bulk. A model of the interface between a Ag(111) electrode and an alkaline electrolyte is discussed.