Nano-sized water bubbles filmed forming out of air

Thanks to a new technique, scientists have directly observed nanoscale water bubbles forming with the metal palladium as a catalyst for the first time .

(Video: Vinayak Dravid/Northwestern University)

A team of researchers from Northwestern University in Illinois has developed a new method for observing and analyzing gas molecules in real time , IFL Science reported on October 1. The method involves trapping gas molecules in a honeycomb-shaped nanoreactor using an ultra-thin glass membrane, then observing them using a high-vacuum transmission electron microscope.

Using a new technique, the team solved a mystery that has been around for hundreds of years: how the rare metal palladium acts as a catalyst and quickly produces water from hydrogen and oxygen. The new study was published in the journal Proceedings of the National Academy of Sciences.

As a result, the team was surprised to see hydrogen enter the palladium, and then a nano-sized bubble of water formed. "We thought this might be the smallest bubble ever formed and directly observed. This was not what we expected. Luckily, we were able to image it," said Yukun Liu, lead author of the study.

Water bubbles formed from palladium metal.

In addition to the photographic evidence, the team also analyzed the bubbles using Electron Energy Loss Spectroscopy (EELS) — the same technique that India's Chandrayaan-1 spacecraft used to confirm the presence of water on the Moon — at the nanoscale.

"By directly observing water generation at the nanoscale, we were able to identify the optimal conditions for rapid water generation under ambient conditions. These findings have important implications for practical applications, such as enabling rapid water generation in deep space using gases and metal catalysts without the need for extreme reaction conditions," added Vinayak Dravid, senior author of the study.

The team also found that the order in which hydrogen and oxygen were added significantly affected the rate at which palladium formed water. Specifically, adding hydrogen first, then oxygen, resulted in the fastest reaction. Because hydrogen atoms are so small, they can squeeze in between palladium atoms, causing the metal to expand. After filling the palladium with hydrogen, the scientists added oxygen.

In addition to observing this process at a microscopic scale, the new research could also lead to better water production techniques. One area where this technology is expected to play an important role is space travel. With palladium pre-filled with hydrogen, astronauts would only need to add oxygen to create drinking water . Water is an essential resource for missions to visit or establish bases on distant planets.