Laser-Engineered Iridium-Based Nanoparticles with High Activity and Stability

Designing high-performance, stable catalysts is essential for electrochemical hydrogen production. Crystalline iridium oxide is one of the few materials that remain stable under the harsh acidic conditions of polymer electrolyte membrane water electrolysis (PEMWE). However, its low activity and iridium scarcity require strategies to enhance atomic utilization. Conventional high-temperature post-synthetic processing increases the share of rutile-phase iridium oxide while promoting particle growth, reducing catalytic activity due to a diminished surface area. Here we present a laser-induced nano oven method using a silicon dioxide matrix as a nanoscale reaction chamber, enabling solid-state nanoparticle synthesis under ambient conditions while preventing agglomeration and allowing precise size control. The synthesized ultra-small crystalline rutile iridium oxide of ~2 nm achieves a high mass activity of 350 ± 15 A gIr-1 at 300 mV overpotential. Analysis using a channel flow cell with on-line inductively coupled plasma mass spectrometry confirms that laser-engineered iridium oxide exhibits superior stability compared to commercial iridium oxide, achieving an optimal balance of activity and stability. Operando electron impact mass spectrometry provided the synthesis mechanistic insights, demonstrating the potential of this strategy for synthesizing ultra-small crystalline metals and metal oxides for various applications.