When Is Nanoconfined Water Different From Interfacial Water?

Fuente: arXiv
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Autores principales: Advincula, Xavier R., Schran, Christoph, Michaelides, Angelos
Formato: Preprint
Publicado: 2025
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author Advincula, Xavier R.
Schran, Christoph
Michaelides, Angelos
author_facet Advincula, Xavier R.
Schran, Christoph
Michaelides, Angelos
contents Water behaves very differently at surfaces and under extreme confinement, but the boundary between these two regimes has remained unclear. Despite evidence that interfacial effects persist under sub-nanometre confinement, the molecular-scale behaviour and its evolution with slit width remain unclear. Here, we use machine-learning molecular dynamics with first-principles accuracy to probe water at graphene surfaces across slit widths ranging from the open-interface limit to angstrom-scale confinement. We find that water undergoes a sharp structural transition: when three or more water layers fit between the walls, the structure of the graphene-water interface is effectively indistinguishable from that in an open system, with density layering, hydrogen bonding, and orientational ordering retaining interfacial character. Below this threshold, however, angstrom-scale confinement strongly reorganises the liquid, producing enhanced ordering, a restructured hydrogen-bond network, and modified orientational motifs. These results establish a molecular-level picture that clearly separates interfacial behaviour from genuine nanoconfinement and provide guidance for predicting and controlling the structure of water in nanoscale solid-liquid environments.
format Preprint
id arxiv_https___arxiv_org_abs_2512_11766
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle When Is Nanoconfined Water Different From Interfacial Water?
Advincula, Xavier R.
Schran, Christoph
Michaelides, Angelos
Chemical Physics
Mesoscale and Nanoscale Physics
Water behaves very differently at surfaces and under extreme confinement, but the boundary between these two regimes has remained unclear. Despite evidence that interfacial effects persist under sub-nanometre confinement, the molecular-scale behaviour and its evolution with slit width remain unclear. Here, we use machine-learning molecular dynamics with first-principles accuracy to probe water at graphene surfaces across slit widths ranging from the open-interface limit to angstrom-scale confinement. We find that water undergoes a sharp structural transition: when three or more water layers fit between the walls, the structure of the graphene-water interface is effectively indistinguishable from that in an open system, with density layering, hydrogen bonding, and orientational ordering retaining interfacial character. Below this threshold, however, angstrom-scale confinement strongly reorganises the liquid, producing enhanced ordering, a restructured hydrogen-bond network, and modified orientational motifs. These results establish a molecular-level picture that clearly separates interfacial behaviour from genuine nanoconfinement and provide guidance for predicting and controlling the structure of water in nanoscale solid-liquid environments.
title When Is Nanoconfined Water Different From Interfacial Water?
topic Chemical Physics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2512.11766