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SUMMARY:Nanoconfined Superionic Water is Molecular Superionic - Dr Samuel 
 Coles\, University of Cambridge
DTSTART:20250514T133000Z
DTEND:20250514T143000Z
UID:TALK224704@talks.cam.ac.uk
CONTACT:Lisa Masters
DESCRIPTION:Superionic ice\, where water molecules dissociate into a latti
 ce of oxygen ions and a rapidly diffusing “gas” of protons\, represent
 s an exotic state of matter with broad implications for planetary interior
 s and energy applications [1\,2]. Recently\, a nanoconfined superionic sta
 te of water has been predicted [3\,4]\, which exists at far milder tempera
 tures than conventional superionic ices and at pressures similar to those 
 created naturally in Van der Waals materials [5]. Interestingly\, in sharp
  contrast to bulk ice\, this phase is comprised of intact water molecules.
  This molecular superionic behaviour has possible applications in a range 
 of electrochemical and electrocatalytic applications. However\, at present
 \, we lack the design principles necessary to design other materials with 
 these properties.\n\nIn this talk\, I will use machine learning and electr
 onic structure simulations to establish how nanoconfined water can be both
  molecular and superionic. We also explore what insights this material off
 ers for superionic states in general. Similar to bulk superionic ice and o
 ther superionic materials [6]\, nanoconfined water conducts via concerted 
 chain-like proton migrations\, which cause the rapid propagation of defect
 s [7]. However\, unlike other molecular phases of water\, its exceptional 
 conductivity arises from: (i) low barriers to proton transfer\; and (ii) a
  flexible hydrogen-bonded network. We propose that these are two key chara
 cteristics of fast ionic conduction in molecular superionics. The insights
  obtained here establish design principles for the discovery of other mole
 cular superionic materials\, with potential applications in energy storage
  and beyond.\n \nReferences:\n1. Matusalem F et al. (2022) Plastic deforma
 tion of superionic water ices. Proc Natl Acad Sci\nUSA119(45):e2203397119.
  https://doi.org/10.1073/pnas.2203397119\n2. Cheng B et al. (2021) Phase b
 ehaviours of superionic water at planetary conditions. Nat \nPhys 17(11):1
 228–1232. https://doi.org/10.1038/s41567-021-01334-9\n3. Kapil V et al. 
 (2022) The first-principles phase diagram of monolayer nanoconfined water.
  \nNature 609(7927):512–516. https://doi.org/10.1038/s41586-022-05036-x\
 n4. Ravindra P et al. (2024) Nuclear quantum effects induce superionic pro
 ton transport in \nnanoconfined water. arXivpreprint arXiv:2410.03272. htt
 ps://arxiv.org/abs/2410.03272\n5. Algara-Siller G et al. (2015) Square ice
  in graphene nanocapillaries. Nature \n519(7544):443–445. https://doi.or
 g/10.1038/nature14295\n6. Morgan BJ (2021) Mechanistic origin of superioni
 c lithium diffusion in anion-disordered \nLi₆PS₅X argyrodites. Chem Ma
 ter 33(6):2004–2018. \nhttps://doi.org/10.1021/acs.chemmater.0c03738\n7.
  Catlow CRA (1990) Atomistic mechanisms of ionic transport in fast-ion con
 ductors. J Chem\nSoc\, Faraday Trans86(8):1167. https://doi.org/10.1039/FT
 9908601167
LOCATION:Unilever Lecture Theatre\, Yusuf Hamied Department of Chemistry
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