In the global effort to fight climate change, hydrogen is emerging as a powerful clean fuel—one that can power factories, vehicles, and even cities without producing carbon emissions.
However, producing hydrogen sustainably using water and renewable energy has long faced a major hurdle: the high cost and scarcity of a rare metal called iridium.
Now, researchers at Rice University have made a breakthrough that could make green hydrogen much more affordable and scalable.
The team has developed a new catalyst that slashes iridium use in water electrolyzers—the machines that split water into hydrogen and oxygen—by more than 80% while maintaining top industrial performance for over 1,500 hours of continuous operation.
Their findings were published in Nature Nanotechnology.
“This is a significant step toward making green hydrogen more accessible and scalable,” said Haotian Wang, associate professor of chemical and biomolecular engineering at Rice.
“By reducing iridium use by over 80%, we’re tackling one of the biggest economic and supply chain bottlenecks in the hydrogen industry.”
Iridium is prized because it can endure the extreme acidic environment inside proton exchange membrane (PEM) electrolyzers, the most efficient technology for making hydrogen from water.
But it’s also one of the rarest elements on Earth—costing around $160 per gram—and global production is tiny. Current projections suggest that demand from electrolyzers alone could soon consume three-quarters of the world’s supply.
To solve this problem, the Rice team partnered with industry collaborator De Nora Tech and used a mix of computer simulations and lab experiments to design a new atomic structure.
They created a catalyst where small amounts of iridium are embedded inside a framework of ruthenium oxide (RuO₂).
This design stabilizes the material from the inside out, protecting the ruthenium atoms above from dissolving under harsh electrochemical conditions.
“Our simulations revealed that iridium atoms just below the surface play a key role in stabilizing the structure,” explained Thomas Senftle, associate professor of chemical and biomolecular engineering at Rice.
“They act like hidden supports that prevent the ruthenium from breaking down.”
The resulting catalyst, named Ru₆IrOₓ, uses a ruthenium-to-iridium ratio of six to one.
It achieved exceptional durability, operating at industrial current densities—2 amperes per square centimeter—for more than 1,500 hours with minimal degradation.
When tested in a 25-square-centimeter PEM electrolyzer at De Nora Tech, the catalyst matched the performance of pure iridium systems while using just a fraction of the metal.
An economic analysis showed that this new approach could reduce anode catalyst costs by more than 80%, making hydrogen production far less dependent on rare materials and volatile prices.
Beyond its immediate economic benefits, the discovery represents a new strategy for designing catalysts: reinforcing materials from within instead of simply coating them for protection.
“This breakthrough could accelerate the global adoption of green hydrogen,” Wang said. “If we can build electrolyzers that are cheaper, more durable, and less reliant on scarce metals, hydrogen can finally become a truly sustainable global fuel.”
The project also involved advanced microscopy and spectroscopy work at Oak Ridge National Laboratory and Brookhaven National Laboratory, demonstrating how collaboration between academia, industry, and national labs can drive major advances in clean energy.
