Investigating states of gas in water encapsulated between graphene layers

Conventionally, only two states are assumed to exist in water: well-dispersed gas monomers and gas bubbles. Rarely is this paradigm explored experimentally. To close this gap, here we used transmission electron microscopy (TEM) to study degassed water, deionized water, and gas-supersaturated water encapsulated in graphene liquid cells. While neither degassed water nor deionized water yielded specific features, two major microscopic structures were evident in gas-supersaturated water: (1) polycrystalline nanoparticles formed of gas molecules and (2) a high density of tiny cells. Dark-field TEM imaging revealed that water molecules surrounding each cell form crystalline structures-a surprising discovery of a clathrate state in gas-supersaturated water that may help resolve several long-standing puzzles. Overall, this study suggests that water may form a matrix that actively interacts with gas molecules in complex and subtle ways.

Automated summary

This study used transmission electron microscopy to investigate the microstructure of degassed water, deionized water, and gas-supersaturated water, revealing two major structures in the latter and the surprising discovery of clathrate-like water crystalline structures. The findings suggest that water may play a more active role in interacting with gas molecules than previously thought.