Single platinum atoms spotted in 2D lattice for first time unlock smarter gas sensors
Austrian scientists have achieved a breakthrough by embedding individual platinum atoms into an ultrathin material and pinpointing their positions within the lattice with atomic precision for the first time ever.
The research team from the University of Vienna and the Vienna University of Technology (TU Wien), utilized a new method that combines defect engineering in the host material, the controlled placement of platinum atoms, and a cutting-edge, high-contrast electron imaging technique known as ptychography.
Jani Kotakoski, PhD, an expert in the field of physics in nanostructured materials and research group leader, highlighted that the achievement sets the stage for tailoring materials with atomic precision.
Active centers, which are tiny sites on the material's surface where chemical reactions occur or gas molecules can specifically bind, are crucial for enhancing the efficiency, selectivity, and overall performance of materials used in catalysis and gas detection.
These centers are especially effective when made up of single metal atoms like platinum, which they aimed not only to produce, but also to visualize with atomic-level precision.
Known for its highly tunable structure, the host material molybdenum disulfide (MoS₂) is an ultrathin semiconductor. To introduce new active sites, the scientists used helium ion irradiation to deliberately create atomic-scale defects on its surface, such as sulfur vacancies.
These vacancy sites were then selectively filled with individual platinum atoms, allowing the team to engineer the material at the atomic level. This precise atomic substitution, known as doping, enables fine-tuning of the material's properties for specific applications, such as catalysis or gas detection.
However, previous studies had not provided direct evidence of the exact positions of foreign atoms within the atomic lattice, as conventional electron microscopy lacks the contrast needed to clearly distinguish between defect types such as single and double sulfur vacancies.
In a bid to address the challenge, the team has now used a state-of-the-art imaging method known as Single-Sideband Ptychography (SSB), which analyzes electron diffraction patterns to achieve atomic-level resolution.
"With our combination of defect engineering, doping, and ptychography, we were able to visualize even subtle differences in the atomic lattice - and clearly determine whether a platinum atom had been incorporated into a vacancy or merely resting loosely on the surface," David Lamprecht, MSc, a student at the University of Vienna's institute for microelectronics, and lead author of the study, said.
With the help of computer simulations, the scientists were able to precisely identify the different incorporation sites, such as positions originally occupied by sulfur or molybdenum atoms, marking a key advance toward targeted material design.
The team believes that combining targeted atom placement with atomically precise imaging unlocks new possibilities for advanced catalyst design and highly selective gas sensing.
While individual platinum atoms placed at precisely defined sites can serve as highly efficient catalysts, like in eco-friendly hydrogen production, the material can also be tailored to respond selectively to specific gas molecules.
"With this level of control over atom placement, we can develop selectively functionalized sensors - a significant improvement over existing methods," Kotakoski concluded in a press release.
According to the research team, the approach is not limited to platinum and molybdenum disulfide but can also be applied to a wide range of 2D materials and dopant atom combinations.
By gaining more precise control over defect creation and incorporating post-treatment steps, the researchers now hope to further refine the technique. Their final goal is to develop functional materials with customized properties, in which every atom is positioned with absolute precision.
The study has been published in the journal Nano Letters.
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When climbing the world's tallest mountains, what counts as cheating?
To reach the highest point on Earth, average climbers need around three to four weeks to let their bodies acclimatize on the ascent and descent. To cut that time to only seven days, mountain climber Lucas Furtenbach is offering a chemical boost with xenon, an inert gas that is mainly used as an anesthetic. Photograph by Cory Richards, Nat Geo Image Collection In 1978, Austrian physician and mountaineer Oswald Oelz was a team doctor on an expedition to Mount Everest when climbers Reinhold Messner and Peter Habeler became the first people to reach its summit without supplemental oxygen. Before then, it was unthinkable that humans, unassisted, could climb 29,032 feet, the height of Everest, where due to drop in atmospheric pressure we inhale only about 30 percent of the oxygen we breath at sea level. Almost half a century later, Oelz's grand-nephew, Austrian climbing guide Lukas Furtenbach, was the architect of a new feat atop Mount Everest. 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Right, a mountaineer descends to camp III during an attempt to summit Hkakabo Razi, said to be Southeast Asia's tallest mountain. Photograph by Aaron Huey, Nat Geo Image Collection (Top) (Left) and Photograph by Renan Ozturk, Nat Geo Image Collection (Bottom) (Right) Not everyone with high-altitude expertise is convinced that xenon is the best way to quickly climb Everest. Some experts argued that a one-week ascent might be possible without a miracle drug like xenon, if only the climbers would use a high enough flow of oxygen right from the bottom. 'If you have a big flow of oxygen, you don't need to work as hard to acclimatise. From an oxygen perspective, you're not going to the summit of Everest, but much lower,' says Mike Grocott, professor of anaesthesia and critical care at the University of Southampton in England and expert on the physiology of hypoxia. This theory, too, was tested this May when Ukraine-born Andrew Ushakov stated that he climbed to the top of Everest in a little less than four days after leaving New York. To achieve this, he used supplemental oxygen and trained in low-oxygen conditions. A team from the Elite Exped company guided Ushakov to the top. He says he used oxygen as soon as he started his ascent from the base camp, starting with a flow of 0.5 liters per minute and slowly increasing it to three to four liters per minute, which he used on the summit day. The xenon team, Furtenbach says, didn't start using oxygen until they reached 19,700 feet, continuing from there with a usual flow of 1 to 2 litres per minute. Higher flow was used only above 26,000 feet. This theoretically means xenon could indeed have some effect on the acclimatisation process, beyond supplemental oxygen. 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This creature can 3D-print its own body parts
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'For me, the most fascinating part is the fact that such a group of animals managed to adapt to different habitats, which caused an immense variety of organ system adaptations and changing body plans,' says Conrad Helm, a biologist at the University of Göttingen in Germany. 'So, most of them look quite bizarre and fascinating and are totally different from the picture most people have in mind when thinking of a worm.' For instance, bristle worms use their bristles to swim through open water, shuffle along the seafloor in a manner that resembles walking, and even dig tunnels. The bristles can also sometimes be equipped with hooks, stylets, and teeth, which allow the worms to secure themselves to their burrows. Interestingly, the authors were able to observe how such structures are formed in the new research, revealing that teeth are also laid down by the 3D-printing-like process as the overall bristle is formed, sort of like a conveyor belt. 'Every 30 to 40 minutes, a tooth is initiated,' says Ikeda, a cell biologist at the University of Vienna and lead author of the study. 'So, a new tooth is starting while the old one is synthesized.' All of these structures are made out of chitin, which is the second most common biopolymer on Earth, and importantly, one that is tolerated really well by the human body. This may mean that by studying polychaete bristles, scientists can develop new surgical stitches or adhesives that start out strong but are eventually absorbed into the human body. There are also plans to develop a new kind of cement for dental work, say the researchers. Helm says the new study only makes him more curious about these weird and wonderful creatures. 'It's really mind-blowing to see how nature is able to create a diversity of shapes and forms that humans are unable to replicate,' he says. 'What is groundbreaking in the new study is the fact that [the researchers] uncovered several ultrastructural and molecular details that were not known to science so far. Especially when it comes to the shaping of the bristles.' He notes that it goes to show how important it is to conduct unbiased, basic research. 'Without basic research, such biological materials or processes will never be usable for medical applications,' he says. 'The study shows that there are still many open questions.' Worms have been on this planet for more than 500 million years—which is about 100 million years before trees existed. Who knows what else these often-overlooked lifeforms have to teach us?
