Electro-Freezing of Supercooled Water Is Induced by Hydrated Al3+ and Mg2+ Ions: Experimental and Theoretical Studies

Leah Fuhrman Javitt, Surajit Kalita, Kshatresh Dutta Dubey, David Ehre, Sason Shaik, Meir Lahav, Igor Lubomirsky

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3 Scopus citations

Abstract

This work reports that the octahedral hydrated Al3+ and Mg2+ ions operate within electrolytic cells as kosmotropic (long-range order-making) “ice makers” of supercooled water (SCW). 10-5 M solutions of hydrated Al3+ and Mg2+ ions each trigger, near the cathode (−20 ± 5 V), electro-freezing of SCW at −4 °C. The hydrated Al3+ ions do so with 100% efficiency, whereas the Mg2+ ions induce icing with 40% efficiency. In contrast, hydrated Na+ ions, under the same experimental conditions, do not induce icing differently than pure water. As such, our study shows that the role played by Al3+ and Mg2+ ions in water electro-freezing is impacted by two synchronous effects: (1) a geometric effect due to the octahedral packing of the coordinated water molecules around the metallic ions, and (2) the degree of polarization which these two ions induce and thereby acidify the coordinated water molecules, which in turn imparts them with an ice-like structure. Long-duration molecular dynamics (MD) simulations of the Al3+ and Mg2+ indeed reveal the formation of “ice-like” hexagons in the vicinity of these ions. Furthermore, the MD shows that these hexagons and the electric fields of the coordinate water molecules give rise to ultimate icing. As such, the MD simulations provide a rational explanation for the order-making properties of these ions during electro-freezing.

Original languageEnglish
Pages (from-to)18904-18911
Number of pages8
JournalJournal of the American Chemical Society
Volume145
Issue number34
DOIs
StatePublished - 30 Aug 2023
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society

Funding

The authors thank Isabelle Weissbuch for her help and perspective on the project. As well as Shiri Dishon Ben Ami for her active research discussion. Additionally, we thank the Israeli Science Foundation (1898/22), the Weizmann SABRA─Yeda-Sela─WRC Program (2021-P133995), and the Ilse Katz Institute for Material Sciences and Magnetic Resonance Research. S.S. was supported by the ISF (ISF grant 520/18). K.D.D. acknowledges the Ramalingaswami Re-entry Research Grant (BT/Reentry/RLF/10/2017) and the Shiv Nadar Foundation for financial assistance.

FundersFunder number
Shiv Nadar Foundation
Israel Science Foundation2021-P133995, 520/18, 1898/22, BT/Reentry/RLF/10/2017

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