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Molecular-scale Hydrophilicity Induced by Solute: Molecular-thick Charged Pancakes of Aqueous Salt Solution on Hydrophobic Carbon-based Surfaces

We directly observed molecular-thick aqueous salt-solution pancakes on a hydrophobic graphite surface under ambient conditions employing atomic force microscopy. This observation indicates the unexpected molecular-scale hydrophilicity of the salt solution on graphite surfaces, which is different fro...

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Autores principales: Shi, Guosheng, Shen, Yue, Liu, Jian, Wang, Chunlei, Wang, Ying, Song, Bo, Hu, Jun, Fang, Haiping
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210940/
https://www.ncbi.nlm.nih.gov/pubmed/25348642
http://dx.doi.org/10.1038/srep06793
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author Shi, Guosheng
Shen, Yue
Liu, Jian
Wang, Chunlei
Wang, Ying
Song, Bo
Hu, Jun
Fang, Haiping
author_facet Shi, Guosheng
Shen, Yue
Liu, Jian
Wang, Chunlei
Wang, Ying
Song, Bo
Hu, Jun
Fang, Haiping
author_sort Shi, Guosheng
collection PubMed
description We directly observed molecular-thick aqueous salt-solution pancakes on a hydrophobic graphite surface under ambient conditions employing atomic force microscopy. This observation indicates the unexpected molecular-scale hydrophilicity of the salt solution on graphite surfaces, which is different from the macroscopic wetting property of a droplet standing on the graphite surface. Interestingly, the pancakes spontaneously displayed strong positively charged behavior. Theoretical studies showed that the formation of such positively charged pancakes is attributed to cation–π interactions between Na(+) ions in the aqueous solution and aromatic rings on the graphite surface, promoting the adsorption of water molecules together with cations onto the graphite surface; i.e., Na(+) ions as a medium adsorbed to the graphite surface through cation–π interactions on one side while at the same time bonding to water molecules through hydration interaction on the other side at a molecular scale. These findings suggest that actual interactions regarding carbon-based graphitic surfaces including those of graphene, carbon nanotubes, and biochar may be significantly different from existing theory and they provide new insight into the control of surface wettability, interactions and related physical, chemical and biological processes.
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spelling pubmed-42109402014-11-06 Molecular-scale Hydrophilicity Induced by Solute: Molecular-thick Charged Pancakes of Aqueous Salt Solution on Hydrophobic Carbon-based Surfaces Shi, Guosheng Shen, Yue Liu, Jian Wang, Chunlei Wang, Ying Song, Bo Hu, Jun Fang, Haiping Sci Rep Article We directly observed molecular-thick aqueous salt-solution pancakes on a hydrophobic graphite surface under ambient conditions employing atomic force microscopy. This observation indicates the unexpected molecular-scale hydrophilicity of the salt solution on graphite surfaces, which is different from the macroscopic wetting property of a droplet standing on the graphite surface. Interestingly, the pancakes spontaneously displayed strong positively charged behavior. Theoretical studies showed that the formation of such positively charged pancakes is attributed to cation–π interactions between Na(+) ions in the aqueous solution and aromatic rings on the graphite surface, promoting the adsorption of water molecules together with cations onto the graphite surface; i.e., Na(+) ions as a medium adsorbed to the graphite surface through cation–π interactions on one side while at the same time bonding to water molecules through hydration interaction on the other side at a molecular scale. These findings suggest that actual interactions regarding carbon-based graphitic surfaces including those of graphene, carbon nanotubes, and biochar may be significantly different from existing theory and they provide new insight into the control of surface wettability, interactions and related physical, chemical and biological processes. Nature Publishing Group 2014-10-28 /pmc/articles/PMC4210940/ /pubmed/25348642 http://dx.doi.org/10.1038/srep06793 Text en Copyright © 2014, Macmillan Publishers Limited. All rights reserved http://creativecommons.org/licenses/by-nc-sa/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/4.0/
spellingShingle Article
Shi, Guosheng
Shen, Yue
Liu, Jian
Wang, Chunlei
Wang, Ying
Song, Bo
Hu, Jun
Fang, Haiping
Molecular-scale Hydrophilicity Induced by Solute: Molecular-thick Charged Pancakes of Aqueous Salt Solution on Hydrophobic Carbon-based Surfaces
title Molecular-scale Hydrophilicity Induced by Solute: Molecular-thick Charged Pancakes of Aqueous Salt Solution on Hydrophobic Carbon-based Surfaces
title_full Molecular-scale Hydrophilicity Induced by Solute: Molecular-thick Charged Pancakes of Aqueous Salt Solution on Hydrophobic Carbon-based Surfaces
title_fullStr Molecular-scale Hydrophilicity Induced by Solute: Molecular-thick Charged Pancakes of Aqueous Salt Solution on Hydrophobic Carbon-based Surfaces
title_full_unstemmed Molecular-scale Hydrophilicity Induced by Solute: Molecular-thick Charged Pancakes of Aqueous Salt Solution on Hydrophobic Carbon-based Surfaces
title_short Molecular-scale Hydrophilicity Induced by Solute: Molecular-thick Charged Pancakes of Aqueous Salt Solution on Hydrophobic Carbon-based Surfaces
title_sort molecular-scale hydrophilicity induced by solute: molecular-thick charged pancakes of aqueous salt solution on hydrophobic carbon-based surfaces
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210940/
https://www.ncbi.nlm.nih.gov/pubmed/25348642
http://dx.doi.org/10.1038/srep06793
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