Suppressing Dynamic Lattice Oxygen Evolution in RuO 2 for Durable Proton Exchange Membrane Water Electrolysis at Industrial Current Densities

Ruthenium oxide (RuO 2 ) exhibits high activity for the oxygen evolution reaction (OER) but suffers from severe degradation under the harsh operating conditions of proton exchange membrane water electrolyzers (PEMWEs), especially at high current densities. This study reveals that the accelerated degradation at high current density is driven by potential-dependent Ru–O bond contraction, enhanced bond covalency, and the subsequent activation of lattice oxygen. High crystallinity effectively stabilizes RuO 2 by preventing detrimental structural evolution, thereby eliminating dynamic anion redox under high oxidative potential up to 1.8 V RHE . Based on this principle, RuO 2 featuring high bulk and surface crystallinity and a large surface area (denoted as RuO 2 -HCLA) is prepared via a gel-template pyrolysis method, which exhibits high catalytic stability. As a practical validation, the PEMWE with the RuO 2 -HCLA anode demonstrates a low degradation rate of ∼38.4 μV h –1 at industrial-related conditions (1.5 A cm –2, 60 °C). Notably, the assembled electrolyzer withstands harsh voltage fluctuation scenarios, demonstrating minimal performance loss (∼1%) at 3 A cm –2 after 280 h of fluctuating input (1.5–1.8 V). This work provides a design strategy for durable and high-performance Ru-based anodes.