Monitoring Structural and Morphological Changes of IrOx Nanocatalysts Operando to Enhance Both Catalytic Activity and Stability

Proton exchange membrane water electrolysis (PEMWE) is a promising technology for the production of de-carbonized hydrogen 1. However, the development of PEMWE is hindered by the low efficiency of the anodic oxygen evolution reaction (OER), currently catalyzed by IrOx particles. The annealing of IrOx electrocatalysts has been shown to improve stability at the cost of decreased OER activity. This tradeoff is in response to the annealing's effects on the morphology and the nature of the surface oxides2,3. To determine which parameter (the material structure4, the initial Ir oxidation state5, or both) controls these two antagonist properties, we have synthesized a library of IrOx nanocatalysts with tailored crystallite size, Ir oxidation state, and degree of crystallinity. We propose to investigate their structural and morphological changes operando in the recent PEMWE cell developed at ID31 and to bridge this unique information with the changes in OER activity and stability.