Thanks to new technology, scientists have observed for the first time the formation of nano-sized water bubbles using palladium as a catalyst.
(Video: Vinayak Dravid/Northwestern University)
A research team from Northwestern University in Illinois has developed a new method to observe and analyze gas molecules in real time, as reported by IFL Science on October 1. This method involves trapping gas molecules in a nano-sized honeycomb reactor using ultra-thin glass membranes, followed by observation through high-vacuum transmission electron microscopy.
Using this new technique, the research team explored a mystery that has persisted for centuries: how the rare metal palladium acts as a catalyst to rapidly produce water from hydrogen and oxygen. The new research was published in the Proceedings of the National Academy of Sciences.
As a result, the researchers were surprised to observe hydrogen entering the palladium, leading to the formation of a nano-sized water bubble. “We think this could be the smallest bubble ever formed and directly observed. This was not something we expected. Fortunately, we captured it on film,” said Yukun Liu, the lead author of the study.
Water bubble formed from palladium.
In addition to visual evidence, the team of experts also analyzed the bubbles using Electron Energy Loss Spectroscopy (EELS)—a technique previously used by India’s Chandrayaan-1 spacecraft to confirm the presence of water on the Moon—at the nanoscale.
“By directly observing the process of water formation at the nanoscale, we can identify the optimal conditions for rapidly producing water under environmental conditions. These findings have significant implications for practical applications, such as facilitating quick water production in deep space using gases and metal catalysts without needing extreme reaction conditions,” added Vinayak Dravid, a senior author of the study.
The research team also discovered that the order in which hydrogen and oxygen are introduced significantly affects the rate at which palladium produces water. Specifically, adding hydrogen first and then oxygen results in the fastest reaction rate. Because hydrogen atoms are very small, they can fit between the palladium atoms, causing the metal to expand. After fully infusing palladium with hydrogen, the scientists then add oxygen gas.
Besides observing this process at the nanoscale, the new research could lead to better water production techniques. One area where this technique is expected to play a crucial role is space travel. With palladium pre-infused with hydrogen, astronauts only need to add oxygen to generate drinking water. Water is an essential resource for missions visiting or establishing bases on distant planets.
