Recent Research

Crystalline Water Structure in Room-Temperature Clathrate State: Hydrogen-Bonded Pentagonal Rings

Ching-Hsiu Chen, Wei-Hao Hsu, Ryoko Oishi-Tomiyasu, Chi-Cheng Lee, Ming-Wen Chu, and Ing-Shouh Hwang*
Small Structures 2400594 (2025)

Prof. Ing-Shouh Hwang, Dr. Ching-Hsiu Chen, and Dr. Wei-Hao Hsu at Institute of Physics, in collaboration with Prof. Ming-Wen Chu from National Taiwan University, utilized transmission electron microscopy (TEM) to study gas-supersaturated water encapsulated between graphene layers at room temperature. A novel type of mesoscopic clathrate hydrate structures is identified. In this clathrate state, water molecules form crystalline structures surrounding or between gas-containing cavities (typically 2–4 nm). Various electron diffraction patterns are recorded. The lattice parameters are determined through collaboration with Prof. Oishi-Tomiyasu from Kyushu University, and the crystalline water structure is derived through first-principles calculations performed by Prof. Chi-Cheng Lee from Tamkang University. This crystalline structure consists purely of pentagonal rings of hydrogen-bonded water molecules, and belongs to the space group of P21. The results improve the understanding of interactions among water and small nonpolar molecules and offer insights into the local structures of ambient liquid water. Such an understanding has potential to resolve many mysteries regarding ambient water as well as gas in water. The complete work has been published recently on Small Structures.

Journal Links: https://doi.org/10.1002/sstr.202400594