Hydrophobic Ice Confined between Graphene and MoS2

Abstract

The structure and nature of water confined between hydrophobic molybdenum disulfide (MoS2) and graphene (Gr) are investigated at room temperature by means of atomic force microscopy. We find the formation of two-dimensional (2D) crystalline ice layers. In contrast to the hexagonal ice 'bilayers' of bulk ice, these 2D crystalline ice phases consist of two planar hexagonal layers. Additional water condensation leads to either lateral expansion of the ice layers or to the formation of three-dimensional water droplets on top or at the edges of the two-layer ice, indicating that water does not wet these planar ice films. The results presented here are in line with a recent theory suggesting that water confined between hydrophobic walls forms 2D crystalline two-layer ice with a nontetrahedral geometry and intrahydrogen bonding. The lack of dangling bonds on either surface of the ice film gives rise to a hydrophobic character. The unusual geometry of these ice films is of great potential importance in biological systems with water in direct contact with hydrophobic surfaces.

References in corpus (5)

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• Surface Energy Engineering for Tunable Wettability through Controlled Synthesis of MoS2
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Cited by in corpus (7)

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• Pinpoint pick-up and bubble-free assembly of 2D materials using PDMS/PMMA polymers with lens shapes
• Two-dimensional crystals on adhesive substrates subjected to uniform transverse pressure
• Flattening van der Waals heterostructure interfaces by local thermal treatment
• Insights into regularity of 2D 3d transition metal monocarbides formation
• Variation of Critical Crystallization Pressure for the Formation of Square Ice in Graphene Nanocapillaries
• Correlation between 2D Square Ice and 3D Bulk Ice by Critical Crystallization Pressure