en.Wedoany.com Reported - Researchers from the University of Adelaide, in collaboration with Tohoku University, Tokyo University of Science, and Vanderbilt University, have successfully developed a microscopic catalyst composed of just 15 iridium atoms. Its mass activity is 1.5 times that of commercially available iridium catalysts, and it exhibits excellent durability, promising to improve green hydrogen production.
Green hydrogen is produced by splitting water into hydrogen and oxygen using renewable electricity. The oxygen evolution reaction (OER) in this process occurs in a highly acidic and corrosive environment, and iridium is one of the few catalyst materials that can withstand such conditions. However, its high cost and limited resources have led researchers to seek ways to maximize its reaction activity while reducing the amount of this rare metal used.
Fabricating atomically precise metal nanoclusters is one approach to reducing iridium usage. Shrinking metal particles to clusters of 1 nanometer (nm) increases the specific surface area and active sites, but iridium is prone to oxidation when exposed to air, making it unstable. To address this, the research team designed a polyol reduction method using ethylene glycol, combined with a ligand exchange process to protect the iridium atoms.
By encapsulating the iridium atom core with carbon monoxide and triphenylphosphine molecules, the researchers obtained iridium nanoclusters composed of 15 atoms. Even when synthesized in a completely open-air environment, these clusters remained highly stable and resistant to oxidation. Subsequently, the researchers attached these nanoclusters to a carbon black support, forming a solid catalyst with an average particle size of 0.9 nanometers.
Test results showed that the mass activity of this new material is approximately 1.5 times that of traditional commercial iridium catalysts, and it can operate continuously for over 20 hours without significant performance degradation. Further analysis revealed that the ultra-miniaturization of iridium particles altered their electronic properties, enabling chemical reactions to occur more efficiently.
Yuichi Negishi, a representative from Tohoku University, stated that this discovery is expected to improve green hydrogen production and provide a new direction for developing cost-effective, high-performance metal nanoclusters to address urgent global energy and environmental challenges. The related research findings have been published in the Journal of the American Chemical Society.
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