Graphene scientists capture first images of atoms ‘swimming’ in liquid

Graphene scientists at the University of Manchester have created a novel “nanopetri dish” using two-dimensional (2D) materials to create a new method of observing how atoms move in a liquid.

Posting in the newspaper Naturethe team led by researchers based at the National Graphene Institute (NGI) used stacks of 2D materials such as graphene to trap liquids in order to better understand how the presence of liquid changes the behavior of the solid.

The team was able to capture images of individual atoms “swimming” in liquid for the first time. The findings could have a widespread impact on the future development of green technologies such as hydrogen production.

When a solid surface is in contact with a liquid, both substances change their configuration in response to the proximity of the other. Such atomic-scale interactions at solid-liquid interfaces govern the behavior of batteries and fuel cells for clean electricity generation, as well as determining the efficiency of clean water generation and supporting many biological processes.

One of the principal investigators, Professor Sarah Haigh, commented: “Given the widespread industrial and scientific importance of such behaviour, it is truly surprising how much we still have to learn about the fundamentals of how atoms behave on surfaces in contact with liquids. One of the reasons for the lack of information is the absence of techniques capable of producing Experimental data for solid-liquid interfaces”.

Transmission electron microscopy (TEM) is one of the few techniques that allows individual atoms to be viewed and analyzed. However, the TEM instrument requires a high vacuum environment and the structure of materials changes in a vacuum. First author Dr Nick Clark explained: “In our work, we show that misleading information is provided if atomic behavior is studied in a vacuum rather than using our liquid cells.”

Professor Roman Gorbachev has pioneered stacking 2D materials for electronics, but here his group has used those same techniques to develop a “double graphene liquid cell”. A 2D layer of molybdenum disulfide was completely suspended in liquid and encapsulated by graphene windows. This novel design allowed them to provide precisely controlled layers of liquid, allowing unprecedented video to be captured showing individual atoms “swimming”, surrounded by liquid.

By analyzing how the atoms moved in the videos and comparing them to theoretical insights provided by colleagues at the University of Cambridge, the researchers were able to understand the effect of liquid on atomic behavior. The liquid was found to speed up the movement of atoms and also change their preferred resting sites relative to the underlying solid.

The team studied a material that shows promise for the environment hydrogen production but the experimental technology they have developed can be used for many different applications.

Dr Nick Clark said: “This is a landmark achievement and it is only the beginning: we are already looking to use this technique to support the development of materials for sustainable chemical processing, necessary to achieve the world’s net-zero ambitions.”