Failure mechanisms in PEM water electrolyzers

The failure of anode catalysts for the oxygen evolution reaction (OER) in proton exchange membrane (PEM) electrolyzers poses a significant barrier to their commercial deployment. In PEM electrolyzers, anode catalysts typically degrade due to the extremely oxidative environment and low local pH at the anode. Under these harsh conditions, catalysts may dissolve into the electrolyte, detach from the membrane, or become contaminated by impurities. These degradation processes are interconnected and complex, rather than isolated issues. Consequently, improving catalyst materials alone has only a limited impact on the overall system performance. In this perspective, we systematically review the causes of anode catalyst failure and their effects on the PEM electrolyzer stability. We pay special attention to the limitations of current approaches, including material shortcomings, changes in electrode structure, and gaps in system-level strategies. A thorough understanding of these challenges is crucial. Achieving a stable anode for acidic OER requires deep insight into the failure mechanisms under real PEM operating conditions. By integrating advances in catalyst design, electrochemical characterization, engineering solutions, and data-driven methods, we can address these limitations effectively. This comprehensive approach is essential to accelerate the development and enable the widespread adoption of PEM electrolyzers.