Cation-dependent restructure of the electric double layer on CO-covered Pt electrodes: Difference between hydrophilic and hydrophobic cations

Akira Yamakata, Masatoshi Osawa

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Structural changes in water layers on a CO-covered Pt electrode triggered by rapid pulsed laser heating of the interface are studied using potential transient measurements. When the laser energy density is below 20 mJ cm− 2, the water layers undergo a change in orientation, which causes a negative shift in the rest potential that recovers within 20 μs with the cooling of the interface. In contrast, when the laser intensity exceeds 20 mJ cm− 2, the CO is desorbed and the rest potential first experiences a positive shift, which is followed by a negative shift. This positive shift is caused by replacement of the CO by water and subsequent restructuring of the water layer. The restructuring rate depends strongly on the electrolyte cation: the rest potential reaches a maximum value within ~ 100 μs for hydrophilic cations such as H+ and Li+, whereas it takes > 10 ms for hydrophobic cations such as Et4N+ and Bu4N+. Surface-enhanced IR absorption measurements suggest that the water molecules around the hydrophobic cations are more strongly hydrogen-bonded than those around the hydrophilic cations. Because the restructuring involves a reforming of the hydrogen-bonding network at the electric double layer, Et4N+ and Bu4N+, which have more strongly hydrogen-bonded hydration shells, require more time than H+ and Li+.

Original languageEnglish
Pages (from-to)19-24
Number of pages6
JournalJournal of Electroanalytical Chemistry
Volume800
DOIs
Publication statusPublished - Sep 1 2017
Externally publishedYes

Keywords

  • Electric double layers
  • Hydrophilic hydration shell
  • Hydrophobic hydration shell
  • Photodesorption
  • Surface restructure
  • Surface-enhanced IR absorption spectroscopy

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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