Proton exchange membrane (PEM) water electrolyzers are a leading technology for clean hydrogen production, yet their widespread deployment is limited by high cost and insufficient durability, particularly at the anode where the oxygen evolution reaction (OER) occurs under extremely harsh conditions. Commercial systems rely on Ir/Ru-based oxides, which are scarce and intrinsically unstable in these environments. Anode degradation is not a single-material issue but arises from tightly coupled chemical, electrochemical, mechanical, and impurity-driven processes spanning the catalyst, membrane, porous transport layer (PTL), and stack.
At the catalyst level, acidic OER proceeds via adsorbate evolution (AEM) and lattice oxygen mechanisms (LOM). LOM involves lattice O participation, creating oxygen vacancies and highly oxidized Ir/Ru centers that are prone to dissolution. High anodic potentials drive IrO2 and RuO2 into unstable high-valence states, crossing "corrosion thresholds" above which dissolution accelerates exponentially. These processes can be diagnosed via cyclic voltammetry and operando dissolution measurements.
Mechanically, nucleation and collapse of oxygen bubbles at the catalyst–membrane interface generate substantial shear and capillary forces, which, amplified by prior corrosion and vacancy formation, detach nanoparticles and progressively erode the catalyst layer. Impurities such as Cl-, Fe3+, and hardness ions further destabilize the anode by catalyzing corrosion, blocking active sites, forming insulating oxides or scales, and accelerating membrane radical attack and gas crossover.
Support and PTL degradation add another dimension. Carbon supports undergo severe corrosion at anodic potentials, causing loss of surface area, crack formation, and particle detachment. Titanium PTLs, while more corrosion-resistant, passivate to insulating TiO2, sharply increasing interfacial resistance and driving damaging current localization. At the stack level, these coupled phenomena produce non-uniform current distribution, hot spots, and cascading mechanical and chemical failures, while standard laboratory tests overestimate durability.
They argue that overcoming these limitations requires a systemic, multiscale approach. Key priorities include: realistic testing under MEA-integrated, high-current, dynamically loaded conditions; advanced in situ and operando diagnostics to track structure, oxidation state, dissolution, and bubble dynamics; and mechanism-informed lifetime models and accelerated stress tests that reflect industrial operation. Breakthrough materials such as high-entropy oxides, engineered PTLs, and robust interfaces, discovered and optimized via integrated computation, synthesis, and characterization, will be essential. Finally, close collaboration among materials scientists, electrochemists, engineers, data scientists, and industry is needed to construct unified degradation datasets and translate mechanistic insight into durable, cost-effective PEM electrolyzers.
About the Author
Dr. Shaoyun Hao is a postdoctoral researcher at Rice University. He received his received his Ph.D. degree in College of Chemical Engineering from the Zhejiang University of China in 2022. Over the past five years, he has published 14 SCI-indexed papers as the first or corresponding author, including: Science, Nature Energy, Nature Nanotechnology, Nature Communications, ACS Energy Letters, and Applied Catalysis B: Environmental and Energy. His research focuses on developing novel electrochemical catalysts and catalytic electrochemical reactors, and the practical applications of various catalytic reactions in the energy and environmental sectors.
About Carbon Future
Carbon Future ( https://www.sciopen.com/journal/2960-0561 ) is an open access, peer-reviewed, and international interdisciplinary journal sponsored by Tsinghua University and published by Tsinghua University Press. It serves as a platform for researchers, scientists, and industry professionals to share their findings and insights on carbon-related materials and processes, including catalysis, energy storage and conversion, as well as low carbon emission process and engineering. It features cutting-edge research articles, insightful reviews, perspectives, highlights, and news and views in the field of carbon. The article publishing charge is covered by the Tsinghua University Press. Carbon Future aims at being a leading journal in related fields.
