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

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.

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Publication details

The article was received on 04 Oct 2019, accepted on 04 Dec 2019 and first published on 04 Dec 2019


Article type: Communication
DOI: 10.1039/C9CC07769C
Chem. Commun., 2019, Accepted Manuscript

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

    H. H. Kristoffersen, K. Chan, T. Vegge and H. A. A. Hansen, Chem. Commun., 2019, Accepted Manuscript , DOI: 10.1039/C9CC07769C

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