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The first-principles phase diagram of monolayer nanoconfined water

Authors :
Kapil, Venkat
Schran, Christoph
Zen, Andrea
Chen, Ji
Pickard, Chris J.
Michaelides, Angelos
Source :
Nature; September 2022, Vol. 609 Issue: 7927 p512-516, 5p
Publication Year :
2022

Abstract

Water in nanoscale cavities is ubiquitous and of central importance to everyday phenomena in geology and biology. However, the properties of nanoscale water can be substantially different from those of bulk water, as shown, for example, by the anomalously low dielectric constant of water in nanochannels1, near frictionless water flow2or the possible existence of a square ice phase3. Such properties suggest that nanoconfined water could be engineered for technological applications in nanofluidics4, electrolyte materials5and water desalination6. Unfortunately, challenges in experimentally characterizing water at the nanoscale and the high cost of first-principles simulations have prevented the molecular-level understanding required to control the behaviour of water. Here we combine a range of computational approaches to enable a first-principles-level investigation of a single layer of water within a graphene-like channel. We find that monolayer water exhibits surprisingly rich and diverse phase behaviour that is highly sensitive to temperature and the van der Waals pressure acting within the nanochannel. In addition to multiple molecular phases with melting temperatures varying non-monotonically by more than 400 kelvins with pressure, we predict a hexatic phase, which is an intermediate between a solid and a liquid, and a superionic phase with a high electrical conductivity exceeding that of battery materials. Notably, this suggests that nanoconfinement could be a promising route towards superionic behaviour under easily accessible conditions.

Details

Language :
English
ISSN :
00280836 and 14764687
Volume :
609
Issue :
7927
Database :
Supplemental Index
Journal :
Nature
Publication Type :
Periodical
Accession number :
ejs60774812
Full Text :
https://doi.org/10.1038/s41586-022-05036-x