Energy-entropy competition in cation-hydroxyl interactions at the liquid water-Pt(111) interface

Henrik H. Kristoffersen*, Karen Chan, Tejs Vegge, Heine Anton Hansen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Electrochemical reaction rates are sensitive to interactions between electrolyte cations and adsorbed reaction intermediates, e.g., cation-*OH interactions in the oxygen reduction reaction on platinum. Here, we calculate the free energy interaction between adsorbed *OH and K+/Li+ situated at the liquid water-Pt(111) interface using ab initio molecular dynamics (AIMD) and metadynamics. Li+ stabilizes *OH by 0.1 ± 0.1 eV and K+ destabilizes *OH by 0.1 ± 0.1 eV, in qualitative agreement with experimental cyclic voltammogram (CV) measurements. In contrast, the internal energy of *OH is stabilized by 0.3 eV and 0.4 eV for Li+ and K+, respectively. This demonstrates that entropy significantly destabilizes cation-*OH interactions and is vital in order to understand even the relative influence of cations at interfaces.
Original languageEnglish
JournalChemical Communications
Number of pages4
ISSN1359-7345
DOIs
Publication statusAccepted/In press - 2020

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