The Stability Challenges of Oxygen Evolving Catalysts: Towards a Common Fundamental Understanding and Mitigation of Catalyst Degradation.

This Review addresses the technical challenges, scientific basis, recent progress, and outlook with respect to the stability and degradation of catalysts for the oxygen evolution reaction (OER) operating at electrolyzer anodes in acidic environments with an emphasis on ion exchange membrane applications. First, the term "catalyst stability" is clarified, as well as current performance targets, major catalyst degradation mechanisms, and their mitigation strategies. Suitable in situ experimental methods are then evaluated to give insight into catalyst degradation and possible pathways to tune OER catalyst stability. Finally, the importance of identifying universal figures of merit for stability is highlighted, leading to a comprehensive accelerated lifetime test that could yield comparable performance data across different laboratories and catalyst types. The aim of this Review is to help disseminate and stress the important relationships between structure, composition, and stability of OER catalysts under different operating conditions.