"The miniaturization resulted in a 'cationic state' that may facilitate efficient adsorption and reaction of intermediates and promote the lattice oxygen oxidation mechanism."
Atomically Precise Iridium Nanoclusters: A Breakthrough for Green Hydrogen
An international research team has developed a method to synthesize atomically precise iridium nanoclusters (Ir15 NCs) in ambient air. The collaborative effort involved scientists from Tohoku University, Tokyo University of Science, Vanderbilt University, and the University of Adelaide.
The nanoclusters, measuring approximately 1 nm in size, were created using a combination of polyol reduction and ligand-exchange techniques. Carbon monoxide and triphenylphosphine serve as protective molecules, encapsulating the iridium core and ensuring stability in air.
Enhanced Performance for Water Electrolysis
The synthesized Ir15 NCs were dispersed on carbon black to form a catalyst with an average particle size of just 0.9 nm. Electrochemical evaluation revealed significant improvements over conventional commercial iridium catalysts.
- 1.5 times higher mass activity compared to standard counterparts
- Operational stability for over 20 hours without any degradation
Background
The oxygen evolution reaction (OER) is essential for producing green hydrogen via water electrolysis. However, it remains energy-intensive and typically requires iridium—a rare and expensive catalyst—due to the highly corrosive acidic environment. Reducing iridium usage while maintaining activity is a critical goal for commercialization.
Atomically precise nanoclusters offer high surface area and abundant active sites, but they have often been prone to oxidation and instability in air. The research team's approach overcomes this hurdle by encapsulating the iridium core with carbon monoxide and triphenylphosphine, achieving air-stable Ir15 nanoclusters.
The findings were published in the Journal of the American Chemical Society on June 15, 2026.