Technological Innovation Website Editor – 08/01/2022
Illustration and image (detail) of atoms swimming in a liquid.
[Imagem: University of Manchester]
Liquids come into contact with solids all the time, creating essential interfaces for everything from life-sustaining biological processes to industrial processes, batteries, fuel cells and just about anything else we can imagine.
However, we know very little about this fundamental phenomenon.
What we do know is that when a solid surface comes into contact with a liquid, both substances change their configuration in response to each other’s proximity – how, how quickly, and how each substance comes to behave are all still enigmas to be solved.
“Given the broad industrial and scientific importance of this behavior, it is really 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 why so much information is lacking is the lack of techniques capable of producing experimental data for solid-liquid interfaces,” explained Professor Sarah Haigh from the University of Manchester (UK).
The good news is that Professor Haigh’s team has just created a new “nano-petri dish”, allowing for the first time to observe how individual atoms of a solid behave as that solid comes into contact with a liquid.
This is the liquid cell, which allows viewing the solid-liquid interface.
[Imagem: Daniel J. Kelly et al. – 10.1021/acs.nanolett.7b04713]
The team began by stacking layers of a well-studied two-dimensional material, molybdenite. Then they drilled holes in this molybdenum disulfide, covered one side with graphene, inserted liquid, and then capped the other side with graphene as well—the researchers call this device a “dual graphene liquid cell.”
These graphene windows made it possible to create precisely controlled liquid layers, making it possible for the first time to film individual atoms “swimming” surrounded by the liquid.
By analyzing how atoms move, and comparing the images with the theories, the researchers were able to understand the effect of the liquid on atomic behavior.
They found, for example, that the liquid accelerates the movement of atoms, and also that it changes the atom’s preferred resting places in relation to the underlying solid – which was not quite what the theories expected.
“In our work, we have shown that misleading information is provided if atomic behavior is studied in a vacuum, rather than using our liquid cells,” explained researcher Nick Clark, referring to transmission electron microscopes, a technique that allows us to visualize and analyze individual atoms, but which requires a high vacuum environment – and the structure of materials changes in a vacuum.
The team believes that its cells with transparent windows should have a widespread impact on the development of green technologies, such as hydrogen production.
“This is a landmark achievement and just the beginning – we are already looking to use this technique to support the development of materials for the sustainable chemical processing needed to achieve the world’s zero net emissions goals,” said Clark.
Article: Tracking single adatoms in liquid in a Transmission Electron Microscope
Authors: Nick Clark, Daniel J. Kelly, Mingwei Zhou, Yi-Chao Zou, Chang Woo Myung, David G. Hopkinson, Christoph Schran, Angelos Michaelides, Roman Gorbachev, Sarah J. Haigh
Vol.: 18, 2, 1168-1174
Article: Nanometer Resolution Elemental Mapping in Graphene-Based TEM Liquid Cells
Authors: Daniel J. Kelly, Mingwei Zhou, Nick Clark, Matthew J. Hamer, Edward A. Lewis, Alexander M. Rakowski, Sarah J. Haigh, Roman V. Gorbachev
Magazine: Nano Letters
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