Entropy governs the structure and reactivity of water dissociation under electric fields

Fuente: arXiv
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Main Authors: Litman, Yair, Michaelides, Angelos
Format: Preprint
Published: 2025
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author Litman, Yair
Michaelides, Angelos
author_facet Litman, Yair
Michaelides, Angelos
contents The response of water to electric fields is critical to the performance and stability of electrochemical devices, and the selectivity of enzymatic, atmospheric, and organic reactions. A key process in this context is the water (auto)dissociation reaction (WD), which governs acid-base aqueous chemistry and shapes reaction rates and mechanisms. Despite its significance, the thermodynamics of the WD reaction in electrified environments remains poorly understood. Here, we investigate the WD reaction under external electric fields using ab initio molecular dynamics simulations within the framework of the modern theory of polarization. Our results reveal that strong electric fields dramatically enhance the WD reaction, increasing the equilibrium constant by several orders of magnitude. Moreover, we show that the applied field transforms the WD reaction from an entropically hindered process to an entropy-driven one. Analysis shows that this is because the electric field alters the tendency of ions to be structure makers or structure breakers. By highlighting how strong electric fields reshape solvent organization and reactivity, this work opens new avenues for designing aqueous electro-catalysts that leverage solvent entropy to enhance their performance.
format Preprint
id arxiv_https___arxiv_org_abs_2506_11734
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Entropy governs the structure and reactivity of water dissociation under electric fields
Litman, Yair
Michaelides, Angelos
Chemical Physics
The response of water to electric fields is critical to the performance and stability of electrochemical devices, and the selectivity of enzymatic, atmospheric, and organic reactions. A key process in this context is the water (auto)dissociation reaction (WD), which governs acid-base aqueous chemistry and shapes reaction rates and mechanisms. Despite its significance, the thermodynamics of the WD reaction in electrified environments remains poorly understood. Here, we investigate the WD reaction under external electric fields using ab initio molecular dynamics simulations within the framework of the modern theory of polarization. Our results reveal that strong electric fields dramatically enhance the WD reaction, increasing the equilibrium constant by several orders of magnitude. Moreover, we show that the applied field transforms the WD reaction from an entropically hindered process to an entropy-driven one. Analysis shows that this is because the electric field alters the tendency of ions to be structure makers or structure breakers. By highlighting how strong electric fields reshape solvent organization and reactivity, this work opens new avenues for designing aqueous electro-catalysts that leverage solvent entropy to enhance their performance.
title Entropy governs the structure and reactivity of water dissociation under electric fields
topic Chemical Physics
url https://arxiv.org/abs/2506.11734