Customized reaction route for ruthenium oxide towards stabilized water oxidation in high-performance PEM electrolyzers

The poor stability of Ru-based acidic oxygen evolution (OER) electrocatalysts has greatly hampered their application in polymer electrolyte membrane electrolyzers (PEMWEs). Traditional understanding of performance degradation centered on influence of bias fails in describing the stability trend, calling for deep dive into the essential origin of inactivation. Here we uncover the decisive role of reaction route (including catalytic mechanism and intermediates binding strength) on operational stability of Ru-based catalysts. Using MRuO x (M = Ce 4+ , Sn 4+ , Ru 4+ , Cr 4+ ) solid solution as structure model, we find the reaction route, thereby stability, can be customized by controlling the Ru charge. The screened SnRuO x thus exhibits orders of magnitude lifespan extension. A scalable PEMWE single cell using SnRuO x anode conveys an ever-smallest degradation rate of 53 μV h −1 during a 1300 h operation at 1 A cm −2 .