Reversible structural transition in nanoconfined ice

Satarifard, Vahid; Mousaei, Mahdi; Hadadi, F.; Dix, James A.; Fernández, Mario Sobrino; Carbone, Paola; Beheshtian, Javad; Peeters, F. M.; Neek-Amal, M.

doi:10.1103/physrevb.95.064105

Cited by 31 publications

(28 citation statements)

References 37 publications

(37 reference statements)

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“…2d found at low densities. Interestingly, the two monolayers of square ice are out-of-registry (AB stacking) and they are not connected by hydrogen bonds (HBs) 23 , 65 . This is rather unusual since most ices in bulk and confined water are characterized by a continuous hydrogen-bond network.…”

Section: Resultsmentioning

confidence: 99%

Phase Diagram of Water Confined by Graphene

Gao

Giovambattista

Şahin

2018

Sci Rep

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The behavior of water confined at the nanoscale plays a fundamental role in biological processes and technological applications, including protein folding, translocation of water across membranes, and filtration and desalination. Remarkably, nanoscale confinement drastically alters the properties of water. Using molecular dynamics simulations, we determine the phase diagram of water confined by graphene sheets in slab geometry, at T = 300 K and for a wide range of pressures. We find that, depending on the confining dimension D and density σ, water can exist in liquid and vapor phases, or crystallize into monolayer and bilayer square ices, as observed in experiments. Interestingly, depending on D and σ, the crystal-liquid transformation can be a first-order phase transition, or smooth, reminiscent of a supercritical liquid-gas transformation. We also focus on the limit of stability of the liquid relative to the vapor and obtain the cavitation pressure perpendicular to the graphene sheets. Perpendicular cavitation pressure varies non-monotonically with increasing D and exhibits a maximum at D ≈ 0.90 nm (equivalent to three water layers). The effect of nanoconfinement on the cavitation pressure can have an impact on water transport in technological and biological systems. Our study emphasizes the rich and apparently unpredictable behavior of nanoconfined water, which is complex even for graphene.

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Section: Resultsmentioning

confidence: 99%

Phase Diagram of Water Confined by Graphene

Gao

Giovambattista

Şahin

2018

Sci Rep

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“…Computer simulation techniques, like molecular dynamics (MD), can aide in the understanding of confined systems that are hard to investigate experimentally. MD has already been shown to be useful in understanding confined systems, however accurately modeling the phase behavior of unconfined water through MD simulations has already proved to be difficult due to its complex phase diagram . Under confinement, the combination of the limited translational and rotational degrees of freedom and water/surface interactions adds an extra challenge as they can both influence the properties of confined water.…”

Section: Introductionmentioning

confidence: 99%

Why different water models predict different structures under 2D confinement

2018

Self Cite

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Experiments of nanoconfined water between graphene sheets at high pressure suggest that it forms a square ice structure (Algara-Siller et al., Nature, 2015, 519, 443). Molecular dynamics (MD) simulations have been used to attempt to recreate this structure, but there have been discrepancies in the structure formed by the confined water depending on the simulation set-up that was employed and particularly on the choice of water model. Here, using classical molecular dynamics simulations, we have systematically investigated the effect that three different water models (SPC/E, TIP4P/2005 and TIP5P) have on the structure of water confined between two rigid graphene sheets with a 0.9 nm separation. We show that the TIP4P/2005 and the TIP5P water models form a hexagonal AA-stacked structure, whereas the SPC/E model forms a rhombic AB-stacked structure. Our work demonstrates that the formation of these structures is driven by differences in the strength of hydrogen bonds predicted by the three water models, and that the nature of the graphene/water interaction only mildly affects the phase diagram. Considering the available experimental data and first-principle simulations we conclude that, among the models tested, the TIP4P/2005 and TIP5P force fields are for now the most reliable when simulating water under confinement. © 2018 Wiley Periodicals, Inc.

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“…8,28 Besides thermodynamic control parameters, such as pressure or temperature, the phase behavior of water under confinement is affected by the commensurability between the confinement distance and the density of water. 5,8,11,27,28 For example, driven through incommensurate transitions, a transformation from a liquid, to a low-density ice phase, back to a high-density liquid, to finally a high-density ice phase, has been predicted for water nanofilms. 9 In another recent study, it was found that oscillations in the shear viscosity of confined water of several orders of magnitude occur over small variations in the confinement distance (under 1 Å).…”

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confidence: 99%

Coexistence of Multilayered Phases of Confined Water: The Importance of Flexible Confining Surfaces

Pestana

Felberg²,

Head‐Gordon

2018

ACS Nano

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Flexible nanoscale confinement is critical to understanding the role that bending fluctuations play on biological processes where soft interfaces are ubiquitous or to exploit confinement effects in engineered systems where inherently flexible 2D materials are pervasively employed. Here, using molecular dynamics simulations, we compare the phase behavior of water confined between flexible and rigid graphene sheets as a function of the in-plane density, ρ. We find that both cases show commensurate mono-, bi-, and trilayered states; however, the water phase in those states and the transitions between them are qualitatively different for the rigid and flexible cases. The rigid systems exhibit discontinuous transitions between an (n)-layer and an (n+1)-layer state at particular values of ρ, whereas under flexible confinement, the graphene sheets bend to accommodate an (n)-layer and an (n+1)-layer state coexisting in equilibrium at the same density. We show that the flexible walls introduce a very different sequence of ice phases and their phase coexistence with vapor and liquid phases than that observed with rigid walls. We discuss the applicability of these results to real experimental systems to shed light on the role of flexible confinement and its interplay with commensurability effects.

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Reversible structural transition in nanoconfined ice

Cited by 31 publications

References 37 publications

Phase Diagram of Water Confined by Graphene

Phase Diagram of Water Confined by Graphene

Why different water models predict different structures under 2D confinement

Coexistence of Multilayered Phases of Confined Water: The Importance of Flexible Confining Surfaces

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