Electro-freezing of super-cooled water as a chemical process Leah Fuhrman Javitt, David Ehre, Meir Lahav and Igor Lubomirsky Weizmann Institute of Science Rehovot, Israel Electro-freezing of super cooled water (SCW) is a process that has been investigated since 1861, with no clear conclusion on the operation of different mechanisms. Here we propose that electro-freezing close to 0 o C includes a chemical process. (1) By the performance of icing experiments on pyroelectric surfaces, we discovered thatthat trigonal planar ions such as bicarbonates, created by the dissolution of atmospheric CO 2 , NO 3 -+ , guanidinium, and biguanide operate as “ice makers.” These trigonal planar ions stabilize “ice-like” hexagons by their interaction with water molecules. Within the “ice-like” hexagons, hydrogen bonds are replaced by covalent bonds of the trigonal planar ion. 1-4 (2) In a second chemical mechanism, we demonstrated that the hydrated Al +3 and Mg +2 ions, induce by experiments performed within electric cells, icing at -4˚C near nickel cathodes. Those two ions, comprising six coordinated waters which interact with nearer water molecules tend to create ice-like hexagons as supported by Molecular Dynamics Simulations. 5 (3) The third chemical mechanism, which is under current investigation uses electrochemistry to alter the surface of a metallic electrodes, by the creation of structural surface sites that induce epitaxial match to ice to trigger ice nucleation. References 1. Curland, S.; Javitt, L.; Weissbuch, I.; Ehre, D.; Lahav, M.; Lubomirsky, I., Heterogeneous Electrofreezing Triggered by CO2 on Pyroelectric Crystals: Qualitatively Different Icing on Hydrophilic and Hydrophobic Surfaces. Angewandte Chemie International Edition 2020, 59, (36), 15570-15574. 2. Curland, S.; Allolio, C.; Javitt, L.; Dishon Ben-Ami, S.; Weissbuch, I.; Ehre, D.; Harries, D.; Lahav, M.; Lubomirsky, I., Heterogeneous Electrofreezing of Super-Cooled Water on Surfaces of Pyroelectric Crystals is Triggered by Trigonal Planar Ions. Angewandte Chemie International Edition 2020, 59, (36), 15575-15579. 3. Javitt, L. F.; Curland, S.; Weissbuch, I.; Ehre, D.; Lahav, M.; Lubomirsky, I., Chemical Nature of Heterogeneous Electrofreezing of Supercooled Water Revealed on Polar (Pyroelectric) Surfaces. Accounts of Chemical Research 2022 , 1383-1394. 4. Javitt, L. F.; Weissbuch, I.; Ehre, D.; Lubomirsky, I.; Lahav, M., Biguanide as an efficient electrofreezing ice-maker ion of super-cooled water., Journal of Crystal Growth and Design 2022 43-47. 5. Javitt, L. F.; Kalita, S.; Dubey, K. D.; Ehre, D.; Shaik, S.; Lahav, M.; Lubomirsky, I., Electro-freezing of Supercooled Water Is Induced by Hydrated Al 3+ and Mg 2+ ions: Experimental and Theoretical Studies., JACS submitted under revision .
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