In situ Raman Spectroscopy Studies of the Interface Between Silver(111) Electrodes and Alkaline NaF Electrolytes
Journal of Electroanalytical Chemistry
||Adsorbates, Electrode|ectrolyte interface, NaOH + NaF electrolytes, Raman spectroscopy, Silver(111)
Fritz-Haber-h~stitut der Max-Planck-GeseUschaft, Faradayweg 4-6, D-14195 Berlin-Dahlem, Germany
Boreskov Institute of Catalysis, Lavrentjeva 5, 630090 Novosibirsk, Russia
The electrochemical interface between Ag(111) single crystal and NaF + NaOH electrolytes at various pH values has been studied using cyclic voltammetry and in situ Raman spectroscopy. Submonolayer oxidation starts well below bulk silver oxide formation at potential about −0.6 V vs. Hg|HgO electrode at pH 11. Two potential-dependent Raman bands ν1 at 540 to 560 cm−1 and ν2 at 803 to 819 cm−1 in basic NaF electrolytes are attributed to AgOH stretching and AgOH bending vibrations of electrochemisorbed hydroxide species. Strong isotope effect is observed in D2O solutions, ν2 being shifted to values of 550 to 570 cm−1. Fluoride stabilizes the adsorption of hydroxide species. A multistep scheme is proposed that describes the mechanism of formation of hydroxide/oxide species at the considered silver-electrode surface.