Development of a Liquid-Phase Ion Gun and Its Application for Sulfidation of Silver Surface

Abstract

A system for safe generation of sulfide ions was established by using the microelectrode technique in order to investigate sulfidation of the metal surface of silver. Both silver microelectrode sulfidation and silver sulfide reduction on the microelectrode were reversible in Na2S solution and corresponded to Ag2S formation and HS− generation, respectively. Cathodic polarization of Ag2S, which covered the silver microelectrode, in pH 8.4 boric-borate buffer solution successfully generated HS− above a glass or silver substrate. Concentration of HS− in the vicinity of the substrate was dependent on the distance between the microelectrode and the substrate. The silver substrate was locally sulfidated by HS− generated from the microelectrode. However, at potentials higher than 0.14 VRHE, local sulfidation of the silver substrate was independent of the substrate potential. It is thought that mass transport of HS− is dominant for sulfidation of the silver substrate.