Deteriorated Balance between Activity and Stability via Ru Incorporation into Ir-Based Oxygen Evolution Nanostructures

Proton exchange membrane water electrolysis is actively researched to improve the oxygen evolution reaction (OER) for the effective hydrogen production. However, commercialization of application for the electrodes still requires nanostructure integration and further improvements. We studied the effects of representative materials: iridium (has high stability and maintains a high surface area with nanosized pores), ruthenium (has high intrinsic activity but causes structural agglomeration of nanostructures), and osmium (facilitates the formation of nanostructures) in various combinations. As other reported results, it was confirmed that the catalytic activity and stability could be remarkably improved through the alloying with iridium and ruthenium, but the balance between activity and stability was notably deteriorated when a nanostructure was applied. Even in the subsequent annealing steps to preserve its stability, it could not restore the balance due to the aggregation of nanostructures in thermal treatment. Based on these results, we propose OER catalyst design directions that achieve both enhancement of activity and preservation of stability simultaneously.