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arXiv · 2406.18448

On the increase of the melting temperature of water confined in one-dimensional nano-cavities

Flaviano Della Pia·Andrea Zen·Venkat Kapil·Fabian L. Thiemann·Dario Alfè·Angelos Michaelides
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Abstract

Water confined in nanoscale cavities plays a crucial role in everyday phenomena in geology and biology, as well as technological applications at the water-energy nexus. However, even understanding the basic properties of nano-confined water is extremely challenging for theory, simulations, and experiments. In particular, determining the melting temperature of quasi-one-dimensional ice polymorphs confined in carbon nanotubes has proven to be an exceptionally difficult task, with previous experimental and classical simulations approaches report values ranging from $\sim 180 \text{ K}$ up to $\sim 450 \text{ K}$ at ambient pressure. In this work, we use a machine learning potential that delivers first principles accuracy to study the phase diagram of water for confinement diameters $ 9.5 < d < 12.5 \text{ Å}$. We find that several distinct ice polymorphs melt in a surprisingly narrow range between $\sim 280 \text{ K}$ and $\sim 310 \text{ K}$, with a melting mechanism that depends on the nanotube diameter. These results shed new light on the melting of ice in one-dimension and have implications for the operating conditions of carbon-based filtration and desalination devices.

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Flaviano Della Pia, Andrea Zen, Venkat Kapil, Fabian L. Thiemann, Dario Alfè, Angelos Michaelides. 2024-06-26. On the increase of the melting temperature of water confined in one-dimensional nano-cavities. https://doi.org/10.1063/5.0239452

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