Investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulations

Abstract Confinement is known to significantly influence the properties of water, yet the precise mechanisms, particularly within nanotubes of varying diameters, remain under investigation. This study examines how confinement impacts the structural and thermodynamic behavior of water molecules insid...

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Main Authors: Amit Srivastava, Gobind Das, Sufian Abedrabbo, Jamal Hassan, Dirar Homouz
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-025-09436-7
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author Amit Srivastava
Gobind Das
Sufian Abedrabbo
Jamal Hassan
Dirar Homouz
author_facet Amit Srivastava
Gobind Das
Sufian Abedrabbo
Jamal Hassan
Dirar Homouz
author_sort Amit Srivastava
collection DOAJ
description Abstract Confinement is known to significantly influence the properties of water, yet the precise mechanisms, particularly within nanotubes of varying diameters, remain under investigation. This study examines how confinement impacts the structural and thermodynamic behavior of water molecules inside carbon nanotubes (CNTs) with diameters ranging from 0.8 nm to 3.0 nm, across temperatures from 230 K to 420 K. We present findings on entropy, radial density, self-diffusion coefficients, and orientational order parameters derived from molecular dynamics simulations. Our results reveal that in ultra-narrow 0.8 nm CNTs, water molecules forms a single-file arrangement with some offset molecules, leading in two distinct peaks in the density profile, which differs from earlier reports suggesting a single peak for single-file water. In 0.8 nm CNTs, water demonstrates subdiffusive behavior, whereas larger CNTs show Fickian diffusion. Further analysis reveals a shift from non-Arrhenius to Arrhenius thermodynamic behavior along the CNT axis with increasing temperature. Additionally, a freezing transition of water is observed in 1.0 nm CNTs. Entropy analysis suggests that confined water is more stable than bulk water, though this stability is influenced by the degree of confinement. This study provides deeper insights into the structure and dynamics of water under confinement.
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spelling doaj-art-234dd401c83e4d8ea42166a5ee18a7032025-08-20T03:37:24ZengNature PortfolioScientific Reports2045-23222025-07-0115111110.1038/s41598-025-09436-7Investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulationsAmit Srivastava0Gobind Das1Sufian Abedrabbo2Jamal Hassan3Dirar Homouz4Department of Physics, Khalifa University of Science and TechnologyDepartment of Physics, Khalifa University of Science and TechnologyDepartment of Physics, Khalifa University of Science and TechnologyDepartment of Physics, Khalifa University of Science and TechnologyDepartment of Physics, Khalifa University of Science and TechnologyAbstract Confinement is known to significantly influence the properties of water, yet the precise mechanisms, particularly within nanotubes of varying diameters, remain under investigation. This study examines how confinement impacts the structural and thermodynamic behavior of water molecules inside carbon nanotubes (CNTs) with diameters ranging from 0.8 nm to 3.0 nm, across temperatures from 230 K to 420 K. We present findings on entropy, radial density, self-diffusion coefficients, and orientational order parameters derived from molecular dynamics simulations. Our results reveal that in ultra-narrow 0.8 nm CNTs, water molecules forms a single-file arrangement with some offset molecules, leading in two distinct peaks in the density profile, which differs from earlier reports suggesting a single peak for single-file water. In 0.8 nm CNTs, water demonstrates subdiffusive behavior, whereas larger CNTs show Fickian diffusion. Further analysis reveals a shift from non-Arrhenius to Arrhenius thermodynamic behavior along the CNT axis with increasing temperature. Additionally, a freezing transition of water is observed in 1.0 nm CNTs. Entropy analysis suggests that confined water is more stable than bulk water, though this stability is influenced by the degree of confinement. This study provides deeper insights into the structure and dynamics of water under confinement.https://doi.org/10.1038/s41598-025-09436-7
spellingShingle Amit Srivastava
Gobind Das
Sufian Abedrabbo
Jamal Hassan
Dirar Homouz
Investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulations
Scientific Reports
title Investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulations
title_full Investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulations
title_fullStr Investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulations
title_full_unstemmed Investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulations
title_short Investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulations
title_sort investigating the thermodynamics properties of water confined in carbon nanotubes using molecular dynamics simulations
url https://doi.org/10.1038/s41598-025-09436-7
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