A new 'nano-petri dish' has been developed using two-dimensional (2D) materials to create a new method of observing how atoms move in liquid. Researchers at The University of Manchester used stacks of 2D materials including graphene to trap liquid in order to further understand how the presence of liquid changes the behaviour of the solid. The study describing the findings was recently published in the journal Nature.
Atoms Captured ‘Swimming’ In Liquid For The First Time
The scientists captured images of single atoms 'swimming' in liquid for the first time. With the help of these findings, green technologies such as hydrogen production could be enhanced.
A solid surface and a liquid change their configuration in response to the proximity of the other when the solid surface is in contact with the liquid. At these solid-liquid interfaces, atomic scale interactions occur. The behaviour of batteries and fuel cells for clean electricity generation, and determining the efficiency of clean water generation is governed by these atomic scale interactions.
In a statement released by The University of Manchester, Professor Sarah Haigh, one of the lead researchers, said that given the widespread industrial and scientific importance of such behaviour, it is truly surprising how much scientists still have to learn about the fundamentals of how atoms behave on surfaces in contact with liquids. The absence of techniques that can yield experimental data for solid-liquid interfaces is one of the reasons why information is missing, she stated.
What Is TEM?
One of the only few techniques that allows individual atoms to be seen and analysed is transmission electron microscopy (TEM). This is a technique in which a particle beam of electrons is used to visualise specimens and generate a highly-magnified image. The high-energy electrons can be transmitted through the solids to image the internal structure of solids.
A high vacuum environment is used for the TEM instrument to operate. However, the structure of materials changes in a vacuum.
Dr Nick Clark, the first author on the paper, explained that in their work, the researchers showed that misleading information is provided if the atomic behaviour is studied in vacuum instead of using liquid cells.
How Was The Study Conducted?
A team led by Professor Roman Gorbachev from the National Graphene Institute (NGI) developed a 'double graphene liquid cell' by the stacking of 2D materials. The researchers completely suspended a 2D layer of molybdenum disulphide in liquid and encapsulated it using graphene windows. With the help of this novel design, they were able to provide precisely controlled liquid layers. This enabled them to capture videos showing the single atoms 'swimming' around surrounded by liquid.
Findings
Researchers at Cambridge University provided theoretical insights on this behaviour. The scientists at The University of Manchester analysed these insights and also how the atoms moved in the videos. According to the study, this helped them understand the effect of the liquid on atomic behaviour. The motion of the atoms was sped up by the liquid. Also, the liquid changed the preferred resting sites of the atoms with respect to the underlying solid.
Dr Nick Clark said this is a milestone achievement and that the researchers are looking to use this technique to support development of materials for sustainable chemical processing, needed to achieve the world's net zero ambitions.