It’s one of those scientific questions that’s so simple, so fundamental, it’s hard to believe we didn’t have an answer—until now: What does water look like when it’s forming? From oceans to puddles, we know what the end result is, but nobody has ever seen the birth of a new water molecule. As the saying kinda goes, water, water, everywhere, but how it actually forms is so mysterious, it makes us want to drink.
That’s changed, thanks to the work of engineers at Northwestern University. Using a new method to analyze gas molecules, they were able to observe water forming at the smallest scale ever recorded. Not only did they witness the teensy, tiny drop of water form, but they said their experiment could have huge ramifications, both here on Earth, and on other planets.
Palladium is an interesting metal due to its ability to absorb huge amounts of hydrogen. While some chemical reactions require carefully calibrated environments, palladium is able to pull this feat off at room temperature and at normal atmospheric pressures. But the why of it has remained “elusive,” the engineers wrote in their study.
“It’s a known phenomenon, but it was never fully understood,” said Yukun Liu, a PhD candidate who worked on the study, in a statement. “Because you really need to be able to combine the direct visualization of water generation and the structure analysis at the atomic scale in order to figure out what’s happening with the reaction and how to optimize it.”
In January, Northwestern professor Vinayak Dravid unveiled a new technique for looking at atoms, using a membrane that holds gas molecules, which can then be examined under powerful electron microscopes. The new method allowed the molecules to be seen at 0.102 nanometer resolution, about the same size of the smallest molecules.
“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, so we could prove to other people that we weren’t crazy.”
In the journal PNAS, Liu, Dravid, and their colleagues described how they used the technique to observe hydrogen molecules entering palladium. In real time, they saw tiny water bubbles forming on the palladium’s surface.
“We think it might be the smallest bubble ever formed that has been viewed directly,” Liu said. “It’s not what we were expecting. Luckily, we were recording it, so we could prove to other people that we weren’t crazy.”
The method is akin to Matt Damon’s character in The Martian burning rocket fuel to extract hydrogen, and adding oxygen to create water, said Dravid. “Our process is analogous, except we bypass the need for fire and other extreme conditions,” he added. “We simply mixed palladium and gases together.”
To confirm they were observing water, they measured the energy lost from electron scattering during the process. The result was identical to what’s found in the oxygen-bonding process of water.
Because they were able to see what was happening on such a tiny scale, the engineers could begin futzing with the process, getting a more exact idea of the conditions necessary for palladium to generate water. They discovered that exposing the metal to oxygen before hydrogen slowed the reaction rate, while the reverse occurred when hydrogen was added first.
That realization could help fuel future water generation projects, whether they be aimed at bringing water to arid portions of the globe, outer space, or even to other planets. The best part is, the process doesn’t alter the palladium’s molecular makeup, meaning the same piece can be used over and over.
“Palladium might seem expensive, but it’s recyclable,” Liu said. “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 over and over.”
That’s great news, as water is somewhat necessary for any crewed bases on the Moon, or missions to Mars. That’s even better news for Matt Damon, who famously has a bad habit of getting stuck on inhospitable planets.
