Elucidating the Degradation Pathways and Stabilization Strategies for Ultralow-Iridium-Loading Oxygen Evolution Catalysts towards Durable Proton Exchange Membrane Water Electrolysis

The development of proton exchange membrane water electrolysis (PEMWE) technology holds strategic importance for the global transition toward a carbon-neutral future, and significantly contributes to decarbonizing various sectors while creating new economic opportunities in the Hong Kong’s emerging green technology market. To date, the large-scale deployment of PEMWE is critically constrained by its dependence on scarce and expensive noble metal iridium. Current research focuses on developing catalysts with reduced iridium loadings, but these materials typically fail to simultaneously achieve high activity and adequate stability in the anodic oxygen evolution reaction (OER) in acidic environments. While the recently discovered oxygen coupling mechanism (OPM)offers a promising path to overcome the limitations of conventional adsorbate evolution mechanism (AEM) and lattice oxygen mechanism (LOM), its practical implementation in OER faces a critical challenge: the OPM-following catalysts experience gradual performance decay during long-term operation. The fundamental origins of this instability, particularly the potential degradation pathways, remain poorly understood, hindering the rational design of durable low-iridium OER catalysts.Our preliminary research has established a robust platform to address these challenges.We have successfully synthesized a model catalyst featuring atomically dispersed iridium on a manganese oxide support, creating well-defined paired active sites facilitating the OPM pathway. Critically, we have also observed preliminary evidence of performance degradation through transformation from OPM to LOM pathway in less stable catalyst configuration, providing a unique opportunity to systematically elucidate the degradation pathways and stabilization strategies of low-iridium OER catalysts.Based on these preliminary data, this project aims to fundamentally understand and ultimately suppress the degradation of low-iridium OER catalysts through an integrated research approach. First, we will employ controlled synthesis to create catalysts with tunable active-site structures, establishing precise relationships between atomic configuration and OER stability. Second, we will combine isotope-labelled mass spectrometry with operando spectroscopy to identify the OER mechanism and capture its evolution during degradation. Third, we will utilize in-situ elemental analysis and microscopic techniques to track active site dissolution and structural changes,elucidating the structural triggers for the degradation. Finally, the fundamental insights gained will guide the development of stabilization strategies, with the optimized catalysts being demonstrated in practical PEMWE devices.⁠⁠⁠⁠⁠⁠⁠This project will provide fundamental insights into the stability limitations for OER electrocatalysts at the atomic scale. The findings will establish essential theoretical foundations for designing durable low-iridium catalysts, ultimately supporting the advancement of cost-effective green hydrogen production technology in Hong