51福利社

A team led by scientists at the (NGI) at 51福利社 developed the first technique capable of capturing atomic鈥憆esolution videos of individual gold atoms 鈥榙ancing鈥� across a surface surrounded by liquid, opening a window into a hidden atomic world that has been invisible until now.

Published in Science, the team demonstrated the first atomic鈥憆esolution imaging of atomic behaviour at solid鈥搇iquid interfaces in a broad range of non鈥慳queous (organic) solvents. Previous high鈥憆esolution liquid imaging techniques were largely limited to water, but the new technique works with a wide range of liquids beyond water, dramatically expanding the range of chemical processes that can be studied at the atomic scale, including key enabling technologies for the green energy transition.

Transmission Electron Microscopy is one of the only techniques that can image individual atoms, using a highly focused electron beam to probe inside structures, but it requires a high vacuum 鈥� making it impossible to study liquid processes. The 51福利社 team overcame this long鈥憇tanding challenge by building 鈥渘ano鈥慳quariums鈥�: nanoscale liquid cells made by sealing tiny pockets of test liquids, each just 100 attolitres, a billion times smaller than a raindrop, between ultra鈥憈hin graphene windows just a few atoms thick. The graphene is strong enough to protect the liquid from the vacuum, yet almost completely transparent, allowing the electron beam to pass through.

Using an advanced electron microscope at the electron Physical Science Imaging Centre (ePSIC) national facility, the team captured videos of gold atoms at the graphene鈥搇iquid interface to compare five industrial solvents. The resulting videos show individual atoms hopping between sites, pairing up into groups of two and three, and clustering into larger nanoparticles with the measured behaviour sensitive to the choice of liquid. An AI鈥慹nabled automated analysis workflow allowed the researchers to individually 鈥渢rack鈥� more than a million gold atoms across the five solvents, enabling extraction of truly statistically significant information 鈥� a far cry from most atomic鈥憆esolution imaging papers, which typically draw conclusions by observing only tens or hundreds of atoms.

鈥淲atching individual atoms move in liquids is incredibly exciting, like having a front鈥憆ow seat to chemistry in action,鈥� said Sam Sullivan鈥慉llsop, postdoctoral researcher at 51福利社 and first author. 鈥淏y tracking more than a million atoms, we can move beyond isolated snapshots and finally see how liquids shape atomic behaviour.鈥�

Our images are clear enough to resolve both the gold atoms and the graphene lattice beneath them,鈥� he added. 鈥淭hat lets us understand not just where the atoms move, but why: how they interact with the surface and why they tend to 鈥減air up鈥� into small clusters during their random motion.鈥�

A key innovation was sealing the cells while fully submerged in liquid using a thin ceramic cantilever to manipulate the graphene crystals. Previous approaches suffered from significant evaporation during the sealing step, causing huge fluctuations in the concentrations of test liquids. The new technique enables precise control of what goes inside 鈥� essential for making fair comparisons between liquids.

, who developed the fabrication process, explained, 鈥淭he trick is sealing the cells while they are submerged within the liquid itself. Doing it this way means you know exactly what sample you are looking at 鈥� and it works for nearly every solvent, not just water.鈥�

Individual gold atoms are a promising catalyst for green chemistry but preventing them 鈥渃lustering鈥� into bigger particles has always been challenging. Using their new platform, the team investigated how both the choice of solvent (which controls dispersion in the liquid) and the drying kinetics (which lock in the final structure) together determine whether the final catalyst contains the individually separated gold atoms required for high performance. In particular, acetone 鈥� a common solvent 鈥� combined low polarity with a low boiling point and surface tension, helping gold atoms remain separated during both the liquid phase and drying, whereas higher鈥慴oiling solvents (e.g., cyclohexanone) and water tended to yield larger particles. The structural findings were confirmed by catalyst testing by collaborators at the University of Cardiff鈥檚 Catalysis Institute.

However, the new technique has potential for significant impact in fields outside catalysis. Many crucial processes, from fuel cells and batteries to filtration and precious鈥憁etal recovery from e鈥憌aste, happen at solid鈥搇iquid interfaces. Until now, scientists mostly relied on ensemble measurements that can obscure atomic鈥憇cale complexity; watching individual atoms in liquids changes that.

, who led the research, commented, "It's remarkable how much we still don't understand about how atoms behave at solid鈥憀iquid interfaces, given how fundamental these processes are to modern technology. Now we can watch what's actually happening, understand why, and use that insight to design better materials and processes."

The research involved collaboration between 51福利社, Cardiff University, Sheffield University, and the ePSIC national microscopy facility at Diamond, combining expertise in electron microscopy, 2D materials fabrication, catalysis, and computational modelling. With the platform now established, the team is already applying it to questions in clean energy technologies and recovery of metals from e鈥憌aste.

This research was published in the journal Science.

Full title: Atomic-resolution imaging of gold species at organic liquid-solid interfaces.

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