Everyone was taught that water could be gas or ice in the early years. Think again. Scientists from the University of Cambridge have discovered that water in a nano-molecule layer acts neither as a liquid nor a solid phase, becoming highly conductive at high pressures.
Much is known about how "Bulk Water" behaves: it expands when it freezes and has a high boiling point. But when the water is compressed to the nanoscale, the bulk water's properties change dramatically.
By developing new ways to predict unusual behavior with unprecedented accuracy, the researchers have detected a few new phases of water at a molecular level.
The water trapped between membranes or in tiny nanoscale cavities is usual - it can be found in everything from membranes in the human bodies to geological formations. But this new phase of nanoconfined water behaves very differently from the water human drinks.
Currently, the challenges of characterizing the phases of water on the nanoscale have hindered a full knowledge of its behavior.
According to the paper published in the journal Nature, the scientists from Cambridge describe how they have utilized advances in computational approaches to forecasting the phase diagram of a nano-molecule thick layer of water with unprecedented accuracy.
The Cambridge-led team used a combination of computational approaches to enable the first-principles level investigation of an individual layer of water.
Finding the Behavior of the New Phase of Water
The scientists found that water confined to a nano-molecule thick layer goes through several stages, including a "hexatic" phase and a "superionic" phase.
In the hexatic phase, water acts as neither a solid nor a liquid but something in the middle. In the superionic phase, which occurs at higher pressures, the water becomes highly conductive, propelling the protons quickly through ice in a way resembling the flow of electrons in a conductor.
Understanding the behavior of the water at the nanoscale is critical to many new technologies. The success of medical treatment can depend on how the water trapped in small cavities in the human body will react.
With the development of highly conductive electrolytes for batteries, water desalination and the frictionless transport of liquids depend on predicting how confined water will act.
Cambridge's Doctor Venkat Kapil said that fully understanding water behavior is the foundational question for all areas.
The paper's principal author and Yusuf Hamied, a Department of Chemistry doctor, added that their approach will "allow the research of a single layer of water in a graphene-like channel with unprecedented predictive accuracy."
Digital generated image of transparent blue hydrogen atoms against a white background. Sustainable energy concept.
Further Phase Findings
The researcher also found that the nano-molecule thick layer of water within the nanochannel exhibited rich and diverse phase behavior. The approach predicts several phases, including the hexatic phase- an intermediate between liquid and solid- and a superionic phase, in which the water has a high electrical conductivity.
Doctor Kapil said that the hexatic phase agrees with previous theories about two-dimensional materials, and their approach suggests that this phase can be seen experimentally by confining water in a graphene channel.
He then added that the existence of the superionic phase under easily accessible conditions is peculiar, as the phrase is generally found in extreme conditions like the core of Uranus and Neptune. Doctor Kapil mentioned that one way to visualize the phase is where the oxygen atoms form a solid lattice, and protons flow like a liquid through the lattice, just like kids running through a maze.
The team says that the superionic phase could be important for future electrolyte and battery materials as it shows an electrical conductivity 100 to 1,000 times higher than current battery materials.
The results will not only help them understand how water works at the nanoscale but also add that "nanoconfinement" could be a new way to find the superionic behavior of other materials.
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