Wetting Transparency of Graphene: A macroscopic Window but Nanoscopic Mirror

Fuente: arXiv
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Hauptverfasser: Wang, Yongkang, Litman, Yair, Cho, Minhaeng, Cox, Stephen, Bonn, Mischa
Format: Preprint
Veröffentlicht: 2025
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author Wang, Yongkang
Litman, Yair
Cho, Minhaeng
Cox, Stephen
Bonn, Mischa
author_facet Wang, Yongkang
Litman, Yair
Cho, Minhaeng
Cox, Stephen
Bonn, Mischa
contents Graphene supported on a substrate in contact with water underpins a wide range of processes and technologies, yet its wettability remains controversial. Understanding how substrate charges and graphene's properties influence water organization is crucial. Here, we combine heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy with molecular dynamics simulations to investigate CaF$_2$-supported graphene interfaces in contact with water. We find that interfacial water orientation is primarily governed by the CaF$_2$ substrate's pH-dependent local electrostatics, confirming graphene's macroscopic wetting transparency. However, at the nanoscale, graphene's polarizability induces a local inversion of water's molecular orientation above substrate charges, revealing subtle structural ordering that is masked in spatially averaged measurements. These insights elucidate the molecular origins of graphene's wetting behavior and suggest new avenues to tailor interfacial phenomena in graphene-based nanofluidic, sensing, and energy applications.
format Preprint
id arxiv_https___arxiv_org_abs_2511_04930
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Wetting Transparency of Graphene: A macroscopic Window but Nanoscopic Mirror
Wang, Yongkang
Litman, Yair
Cho, Minhaeng
Cox, Stephen
Bonn, Mischa
Chemical Physics
Graphene supported on a substrate in contact with water underpins a wide range of processes and technologies, yet its wettability remains controversial. Understanding how substrate charges and graphene's properties influence water organization is crucial. Here, we combine heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy with molecular dynamics simulations to investigate CaF$_2$-supported graphene interfaces in contact with water. We find that interfacial water orientation is primarily governed by the CaF$_2$ substrate's pH-dependent local electrostatics, confirming graphene's macroscopic wetting transparency. However, at the nanoscale, graphene's polarizability induces a local inversion of water's molecular orientation above substrate charges, revealing subtle structural ordering that is masked in spatially averaged measurements. These insights elucidate the molecular origins of graphene's wetting behavior and suggest new avenues to tailor interfacial phenomena in graphene-based nanofluidic, sensing, and energy applications.
title Wetting Transparency of Graphene: A macroscopic Window but Nanoscopic Mirror
topic Chemical Physics
url https://arxiv.org/abs/2511.04930