Iridium problem of clean hydrogen? Solved in an afternoon with a new megalibrary

For decades, researchers from around the world have looked for alternatives to iridium, an extremely rare and incredibly expensive metal used in the production of clean hydrogen fuels.

Now, a new powerful tool has found one – in a single afternoon.

Invented and developed at the Northwestern University, this tool is called megalibrary. The world’s first “data factory” in the world, each megalibrary contains millions of unique design nanoparticles on a small chip.

In collaboration with researchers from Toyota Research Institute (TRI), the team used this technology to discover commercially relevant catalysts for hydrogen production. Then they increased the material and demonstrated that it could work in a device, all in record time.

With a megalibrary, scientists quickly detected vast combinations of four abundant and inexpensive metals – each known for its catalytic performance – to find a new material with performance comparable to iridium. The team discovered an entirely new material which, in laboratory experiences, corresponded or, in some cases, even exceeded the performance of Iridium -based commercial materials, but at a cost fraction.

This discovery does not only make affordable green hydrogen a possibility; This also proves the effectiveness of the new approach to Megalibrary, which could completely change the way researchers find new materials for a number of applications. The study is published in the Journal of the American Chemical Society.

“We have undoubtedly triggered the most powerful synthetic tool in the world, which makes it possible to search for the enormous number of combinations available for chemists and materials of materials to find materials that matter,” said Chad A. Mirkin of Northwestern, the main author of the study and the main inventor of the megalibrary platform.

“In this particular project, we have channeled this capacity towards a major problem with which the energy sector faces.

Pioneer of nanotechnology, Mirkin is the chemistry teacher at George B. Rathmann at the Weinberg College of Arts and Sciences in Northwestern; Professor of chemical and biological engineering, biomedical engineering and materials and materials of materials at the McCormick School of Engineering; and Executive Director of the International Institute of Nanotechnology.

Mirkin co-directed work with Ted Sargent, Lynn Hopton Davis and Greg Davis chemistry professor at Weinberg, professor of electrical and computer engineering at McCormick and executive director of Paula M. Triens for sustainability and energy.

‘Not enough iridium in the world’

While the world is moving away from fossil fuels and decarbonization, affordable green hydrogen has become a critical piece of the puzzle. To produce clean hydrogen energy, scientists turned to water division, a process that uses electricity to divide water molecules into their two constitutive components: hydrogen and oxygen.

The oxygen part of this reaction, called oxygen evolution reaction (OER), is however difficult and ineffective. The OER is more effective when scientists use Iridium -based catalysts, which have significant drawbacks. Iridium is rare, expensive and often obtained as a sub-product of the platinum exploitation. More value than gold, iridium costs nearly $ 5,000 per ounce.

“There is not enough iridium in the world to meet all of our planned needs,” said Sargent. “While we are thinking of dividing water to generate other forms of energy, there is not enough iridium from a purely supply point of view.”

“ The complete army deployed on a chip ”

Mirkin, who presented the megalibraires in 2016, decided with Sargent that finding new candidates to replace Iridium was a perfect application for its revolutionary tool. Although the discovery of materials is traditionally a slow and intimidating task filled with tests and errors, the megalibraries allow scientists to locate optimal compositions at vertiginous speeds.

It’s time to really find the best materials for each need – without compromise. “”

Each megalibrary is created with paintings of hundreds of thousands of tiny pyramid -shaped advice to print individual “points” on a surface. Each point contains an intentionally designed metal salts mixture. When heated, metal salts are reduced to form unique nanoparticles, each with a specific composition and size.

“You can consider each tip as a small person in a small laboratory,” said Mirkin. “Instead of having a small person to make a structure at a time, you have millions of people. So you essentially have a full army of researchers on a chip.”

And the winner is …

In the new study, the chip contained 156 million particles, each made from different combinations of ruthenium, cobalt, manganese and chrome. A robotic scanner then evaluated how the most promising particles could make a REL. Based on these tests, Mirkin and his team have selected the best efficient candidates to undergo other laboratory tests.

Finally, a composition stood out: a precise combination of the four metals (Ru₅₂Co₃₃Mn₉Crossing₆ oxide). Multi-metal catalysts are known to cause synergistic effects that can make them more active than unique metal catalysts.

“Our catalyst has in fact a little higher activity than iridium and excellent stability,” said Mirkin. “It is rare because often ruthenium is less stable. But the other elements of the composition stabilize ruthenium.”

The ability to filter particles for their ultimate performance is a new major innovation. “For the first time, we were not only able to quickly detect the catalysts, but we saw the best behaving well in a scale on a scale,” said Joseph Montoya, principal sorting researcher and co-author of the study.

In long -term tests, the new catalyst worked for more than 1,000 hours with high efficiency and excellent stability in a hard acid environment. It is also considerably cheaper than iridium – about a sixth of the cost.

“There is a lot of work to do to make this commercially viable, but it is very exciting that we can so quickly identify promising catalysts – not only on a laboratory scale but for devices,” said Montoya.

Just the start

By generating sets of data from high -quality solid quality materials, the megalibrary approach also laid the basics of the use of artificial intelligence (AI) and automatic learning to design the next generation of new materials. Northwestern, TRI and Mattiq, a derivation company from the North West, have already developed automatic learning algorithms to pass through megalibrares at record speeds.

Mirkin says this is only the beginning. With AI, the approach could evolve beyond the catalysts to revolutionize the discovery of materials for almost all technologies, such as batteries, biomedical devices and advanced optical components.

“We are going to look for all kinds of materials for batteries, fusion and even more,” he said. “The world does not use the best materials for its needs. People have found the best materials at some point, given the tools available to them. The problem is that we now have a huge infrastructure built around these materials, and we are stuck with them.

“We want to upset this advantage. It’s time to really find the best materials for all needs – without compromise.”