A new way to study liquid cells has been developed by University of Manchester researchers – and in doing so, they imaged the motion of single atoms in a liquid for the very first time. This achievement might lead to a better understanding of crucial technologies for clean energy generation and important biological processes.
Published in Nature, the team placed a solution of salt water between two layers of graphene, a 2D material made of carbon atoms arranged in a hexagonal grid. Within this cell, they placed a layer of Molybdenum disulfide and platinum atoms.
Using transmission electron microscopy (TEM), the team studied how the platinum atoms move around the surface of the material. TEM requires vacuum conditions, so without the construction of the graphene keeping the liquid confined, it would be impossible to study. Vacuum conditions actually change the behavior of the material.
“In our work we show that misleading information is provided if the atomic behaviour is studied in vacuum instead of using our liquid cells,” first author Dr Nick Clark said in a statement. “This is a milestone achievement and it is only the beginning – we are already looking to use this technique to support development of materials for sustainable chemical processing, needed to achieve the world’s net zero ambitions.”
The platinum atoms were resting on the internal surfaces and the liquid shifted them at a higher speed than they would without liquid. They also discovered that the presence of salty water led to changes in the atoms' preferred resting site on the surfaces.
The work envisions the cells as a way to produce hydrogen in a sustainable way, but that’s only one possible application. Similar cells are used in energy storage and clean water generation, and they could also be used as a proxy for biological systems where liquid and solids interact.
“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 information is missing is the absence of techniques able to yield experimental data for solid-liquid interfaces,” Professor Sarah Haigh, one of the lead researchers, commented.