Palladium can act as a catalyst to generate water rapidly. However, how exactly this reaction occurs has remained a mystery. The phenomenon was never fully understood. To figure out what’s happening, the direct visualization of water generation must be combined with the structure analysis at the atomic scale.
For the first time, Northwestern researchers have witnessed the merging of hydrogen and oxygen atoms to form tiny, nano-sized bubbles of water in real-time and on a nanoscale. This study aimed to understand how Palladium, a rare metallic element, catalyzes the gaseous reaction to generate water. It could be a practical solution for rapidly generating water in arid environments.
Researchers now understand how Palladium catalyzes the gaseous reaction to generate water. They studied reactions at the nanoscale, uncovering the mechanisms involved and discovering new methods to speed up the process.
In January 2024, researchers devised a real-time method to analyze gas molecules. The team developed an ultra-thin glassy membrane that can hold gas molecules within honeycomb-shaped nanoreactors to be viewed within high-vacuum transmission electron microscopes.
The membrane allows scientists to get more information from the sample itself.
Water purification using only a few atoms
What did researchers do?
They mixed Palladium and gases. After verifying that the palladium reaction produced water, the researchers aimed to optimize the process.
They found that introducing hydrogen before oxygen resulted in the quickest reaction. The small hydrogen atoms could infiltrate the Palladium’s structure, causing it to expand.
Once the Palladium was saturated with hydrogen, the researchers added oxygen gas. The hydrogen then reacted with the oxygen, allowing the Palladium to contract back to its original state.
Using the new technology, researchers studied the palladium reaction. They first observed hydrogen atoms infiltrating the Palladium, causing its square lattice to expand. However, they were astonished when they noticed tiny water bubbles forming on the Palladium’s surface.
The physics of bubble evolution
Yukun Liu, the study’s first author and a Ph.D. candidate in Dravid’s laboratory, said, “We think it might be the smallest bubble ever formed that has been viewed directly. It’s not what we were expecting. Luckily, we were recording it to prove to other people that we weren’t crazy.”
According to scientists, larger sheets of Palladium would generate much larger quantities of water. This discovery could be the foundation for preparing hydrogen-filled Palladium before traveling into space.
Liu said, “Palladium might seem expensive, but it’s recyclable. Our process doesn’t consume it. The only thing consumed is gas, and hydrogen is the most abundant gas in the universe. After the reaction, we can reuse the palladium platform repeatedly.”
Journal Reference:
- Yukun Liu, Kunmo Koo, Zugang Mao, and Vinayak P. Dravid. Unraveling the adsorption-limited hydrogen oxidation reaction at palladium surface via in situ electron microscopy. PNAS. DOI: 10.1073/pnas.2408277121