Nanoscale morphological evolution of monocrystalline Pt surfaces during cathodic corrosion.
| Autor: | Arulmozhi N; Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands., Hersbach TJP; Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands., Koper MTM; Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands m.koper@chem.leidenuniv.nl. |
|---|---|
| Jazyk: | angličtina |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2020 Dec 22; Vol. 117 (51), pp. 32267-32277. Date of Electronic Publication: 2020 Dec 07. |
| DOI: | 10.1073/pnas.2017086117 |
| Abstrakt: | This paper studies the cathodic corrosion of a spherical single crystal of platinum in an aqueous alkaline electrolyte, to map out the detailed facet dependence of the corrosion structures forming during this still largely unexplored electrochemical phenomenon. We find that anisotropic corrosion of the platinum electrode takes place in different stages. Initially, corrosion etch pits are formed, which reflect the local symmetry of the surface: square pits on (100) facets, triangular pits on (111) facets, and rectangular pits on (110) facets. We hypothesize that these etch pits are formed through a ternary metal hydride corrosion intermediate. In contrast to anodic corrosion, the (111) facet corrodes the fastest, and the (110) facet corrodes the slowest. For cathodic corrosion on the (100) facet and on higher-index surfaces close to the (100) plane, the etch pit destabilizes in a second growth stage, by etching faster in the (111) direction, leading to arms in the etch pit, yielding a concave octagon-shaped pit. In a third growth stage, these arms develop side arms, leading to a structure that strongly resembles a self-similar diffusion-limited growth pattern, with strongly preferred growth directions. Competing Interests: The authors declare no competing interest. (Copyright © 2020 the Author(s). Published by PNAS.) |
| Databáze: | MEDLINE |
| Externí odkaz: |
|