Formation of porous ice frameworks at room temperature

Yuan Liu, Weiduo Zhu, Jian Jiang, Chongqin Zhu, Chang Liu, Ben Slater, Lars Ojamäe, Joseph S. Francisco, Xiao Cheng Zeng

Research output: Contribution to journalArticlepeer-review


Bulk crystalline ices with ultralow densities have been demonstrated to be thermodynamically metastable at negative pressures. However, the direct formation of these bulk porous ices from liquid water at negative pressures is extremely challenging. Inspired by approaches toward porous media based on host–guest chemistry, such as metal–organic frameworks and covalent organic frameworks, we herein demonstrate via molecular dynamics simulations that a class of ultralow-density porous ices with upright channels can be formed spontaneously from liquid water at 300 K with the assistance of carbon nanotube arrays. We refer to these porous ice polymorphs as water oxygen-vertex frameworks (WOFs). Notably, our simulations revealed that the liquid–WOF phase transition is first-order and occurs at room temperature. All the WOFs exhibited the unique structural feature that they can be regarded as assemblies of nanoribbons of hexagonal bilayer ice (2D ice I) at their armchair or zigzag edges. Based on density functional theory calculations, a comprehensive phase diagram of the WOFs was constructed considering both the thermodynamic and thermal stabilities of the porous ices at negative pressures. Like other types of porous media, these WOFs may be applicable to gas storage, purification, and separation. Moreover, these bio-compatible porous ice networks may be exploited as medical-related carriers.

Original languageEnglish (US)
Article numbere2104442118
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number31
StatePublished - Aug 3 2021
Externally publishedYes


  • Crystalline
  • Ice
  • Porous

ASJC Scopus subject areas

  • General


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