Electrochemistry of Sulfur Adlayers on the Low-Index Faces of Silver

摘要

The formation and reactivity of sulfur adlayers on single-crystal Ag electrodes((111), (110), and (100) orientations) in aqueous solutions (pH = 13) containing HS(-) is reported. Oxidative adsorption of HS(-) (Ag + HS(-) (right arrow) AgSH + e(-)) occurs on all three low-index surfaces at potentials ranging between -0.5 and -0.7V of the thermodynamic value for bulk Ag2S formation. Voltammetric and electrochemical quartz crystal measurements demonstrate that the resulting AgSH adlayer undergoes a second one-electron oxidation (AgSH + Ag + OH(-) (right arrow) Ag2S + H2O + e(-)) at the (111) and (110) surfaces prior to bulk Ag2S formation, yielding an underpotential deposited Ag2S adlayer (surface coverages