| 研究実績の概要 |
Development of a system for safe generation of sulfide ions and sulfidation of a silver surface 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. Generation of HS- ions was strongly dependent on diffusion of HS- ions from the microelectrode to the substrate surface and solution bulk. Concentration of HS- in the vicinity of the substrate was dependent on the distance from the microelectrode to 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. The substrate potential as well as diffusion of HS- influences sulfidation of the silver substrate. Sulfidation by using the Ag/Ag2S microelectrode is safe and effective to investigate the mechanism and kinetics of sulfidation not only on a silver surface but also on various metal surfaces.
|
| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
In my study, I aimed to examine reaction mechanisms and kinetics of depassivation process of stainless steel based on microelectrochemistry of metal sulfides. In order to investigate the role of the metal sulfide which is the origin of pitting of stainless steel, the new corrosion experimental methods were developed that can limit to generate very small amount of sulfide ion by electrochemically controlled systems. Sulfide ion generation and their diffusion phenomena and its application on silver surface had investigated.
|
