Progress of Heterogeneous Iridium-Based Water Oxidation Catalysts

Green hydrogen production relies on efficient water oxidation reactions. The oxygen evolution reaction (OER) is a key step in this process. OER involves multiple intermediates and steps, which slow down the reaction. A high overpotential is required to overcome this sluggishness. Proton exchange membrane electrolyzers are preferred for water splitting. However, their anode catalysts are limited to iridium-based materials. Iridium catalysts have been widely studied for acidic OER. They offer a good balance of activity and stability. Recent research has shown promising developments in this area.

This review aims to summarize the current state of iridium-based catalysts for OER. It focuses on their structure and performance in acidic conditions. The study addresses the need for better catalysts in proton exchange membrane electrolyzers. It highlights the importance of understanding reaction mechanisms. The authors aim to clarify the role of active sites and intermediates. They also examine the impact of catalyst structure on activity. This work provides insights into the latest progress in the field. It sets the stage for future research directions in acidic OER.

The review uses surface and bulk Pourbaix diagrams to analyze iridium species in aqueous solutions. It categorizes catalysts into metallic, oxide, amorphous, and crystalline forms. The study also considers single crystals, atomically dispersed, and nanostructured materials. Different iridium compounds are evaluated for OER performance. The authors examine the latest findings on active sites and reaction intermediates. They analyze reaction kinetics and elementary steps in detail. The review draws from recent experimental and theoretical studies. It synthesizes information from multiple sources to provide a comprehensive overview.

Iridium-based catalysts show high activity and stability for acidic OER. The study identifies key factors influencing catalyst performance. Surface and bulk Pourbaix diagrams explain the stability of iridium species. Active sites and reaction intermediates are well characterized in recent studies. Nanostructured and atomically dispersed catalysts exhibit enhanced activity. The reaction kinetics and elementary steps are better understood now. Iridium compounds offer promising alternatives to traditional materials. The latest findings suggest new directions for catalyst design.

The review highlights the progress in iridium-based catalysts for acidic OER. It emphasizes the importance of catalyst structure on activity and stability. The study shows that active sites and reaction intermediates are well understood. Nanostructured and atomically dispersed materials show promise. The authors suggest that future research should focus on catalyst design. They also recommend further studies on reaction mechanisms. The review concludes that iridium remains a leading material for OER. It sets the stage for continued improvements in catalyst performance.