Operando Insights into Bridging Oxygen‐Driven RuO x Lattice Collapse and its Mitigation Strategy for Durable Industrial PEMWE

Abstract Ruthenium oxide (RuO x ) is a promising anode catalyst for proton exchange membrane water electrolysis (PEMWE), but its degradation mechanism, especially under practical ampere‐level operation, remains elusive. Herein, we established a device‐level diagnostic framework to investigate the evolution of RuO x . Operando PEMWE‐based X‐ray absorption spectroscopy (XAS) revealed a progressive negative shift of the Ru K‐edge. Extended X‐ray absorption fine structure (EXAFS) analysis further showed a pronounced decrease in both Ru–O and Ru–O–Ru coordination, revealing that irreversible loss of bridging oxygen (O bridge ) triggers the final catalyst deactivation. Guided by these insights, we demonstrated that low‐level Ir doping in Ru 0.9 Ir 0.1 O x could notably increase the O bridge vacancy formation energy and thus stabilize the Ru–O framework. Under identical PEMWE operating conditions, the Ru valence state and coordination environment in Ru 0.9 Ir 0.1 O x remain relatively stable. In‐cell electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) analyses confirmed that this structural stabilization strategy effectively maintains low electrode kinetic and proton transport resistances across a range of cell voltages, enabling stable operation at industrially relevant ampere‐level current densities. Finally, the resulting Ru 0.9 Ir 0.1 O x catalyst achieves 1.74 V at 3 A cm −2 and stably operates for 500 h at 1 A cm −2 , outperforming most reported Ru‐based anodes.