Abstract

The structure and reactivity of water in anisotropic environments, such as at interfaces or under the influence of electric fields, can differ significantly from those observed in bulk. Understanding these differences is crucial for gaining insights into various atmospheric and electrochemical processes that impact our society.

In the first part of my talk, I will discuss how ions organize at the water/air interface and demonstrate that the conventional electric double-layer model fails to provide a complete microscopic picture of these interfaces [1,2]. Using first-principles simulations, I will show that the surface of common electrolyte solutions is stratified into two distinct water layers: one depleted of ions and the other enriched with them.

Next, I will present our recent investigation into water autodissociation [3]. We employ the modern theory of polarization to perform periodic ab initio molecular dynamics simulations of water under external electric fields. Our simulations reveal that the enhancement of water dissociation in these conditions is primarily driven by entropic effects rather than enthalpic ones, as is normally assumed. Finally, I will discuss how these findings may provide crucial insights into recent kinetic measurements of the hydrogen evolution reaction (HER) across various electrochemical systems [4].

[1] Y. Litman, J. Lan, Y Nagata, D. M. Wilkins, J. Phys. Chem. Lett. 14, 8175-8182 (2023) [2] Y. Litman, K-Y. Chiang, T. Seki, Y. Nagata, M. Bonn, Nat. Chem. (2024) 16, 644–650 (2024) [3] Y. Litman, A. Michaelides (in preparation) [4] J. M. Gisbert-González, C. G. Rodellar, J. Druce, E. Ortega, B. Roldan Cuenya, S. Z. Oener, J. Am. Chem. Soc (in press, DOI : 10.1021/jacs.4c18638)