Researchers from the Supreme Council for Scientific Research (CSIC) took part in an international study published in Advanced Energy Materials. They identified a compound capable of producing green hydrogen while using ten times less iridium, a scarce and costly transition metal, according to CSIC.
Green hydrogen is produced when water is electrolyzed with renewable energy. This approach is seen as a key step toward a decarbonized society, helping to reduce emissions across industries and transport.
To generate this hydrogen, electrolyzers are required, notably the Proton Exchange Membrane (PEM) type. These devices perform very well and are efficient, but their material costs can be a major hurdle, noted Sergio Rojas, a CSIC researcher at the Institute of Catalysis and Petroleum Chemistry and one of the study’s contributors.
Iridium is not only expensive but also one of the rarest materials widely distributed on Earth, a fact that underlines the importance of reducing its use in catalysts.
CSIC notes that, according to its market assessments, iridium currently trades around $4,600 per ounce (32.15 grams), based on estimates from the Johnson Matthey company.
How are the new improvements achieved?
The researchers designed a metal oxide catalyst that contains ten times less iridium than is common in commercial catalysts. The team reduced the material loading from two milligrams per square centimeter to 0.2 mg/cm², yet retained the same catalytic performance.
“Catalyst cost was reduced tenfold,” commented a CSIC scientist at the Madrid Institute for Materials Science, who is also an author of the study. The work illustrates the potential of basic research as a foundation for applied developments.
Another CSIC researcher emphasized that the work started over a decade ago, but only recently found a viable application. The study’s authors view this as a bridge to practical, scalable catalysts for greener hydrogen production.
María Retuerto, a scientist at the Institute of Catalysis and Petroleum Chemistry and an author of the study, added that the findings open the door to other similarly scalable materials that could advance the field.
Retuerto also explained that scaling this particular compound is challenging because it requires a furnace capable of maintaining an oxygen pressure around 200 bar — a specialized piece of equipment found at the Madrid ICMM facility and used by Alonso for experiments.
According to Retuerto, surface modification of the starting compound drives the observed catalytic activity. There is a possibility that alternative starting materials or surface remodelings could yield similar results, reducing reliance on the exact precursor used in the study.
Rojas noted the potential for producing several tons of material, describing the compound as a catalytic precursor that enables the creation of other catalysts in larger quantities.
The CSIC teams previously described the working mechanism of this catalyst and its derivatives in another article in Nature Communications published at the end of 2022, where they argued that the iridium content in PEM electrolyzers could be lowered without sacrificing performance.
Although alkaline electrolysis remains a strong option, PEM technology offers rapid deployment potential and the ability to produce large amounts of high-purity hydrogen. The challenge remains the iridium required for the anode, a key barrier to market-wide adoption, Retuerto noted.
References and additional reading: [Source attribution: Wiley article, paraphrased for accessibility]
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Open access materials related to this study are available as summarized in the CSIC reports and associated conference notes.
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