Ion Exchange Membranes Prevent Nanobubble Detachment But Do Not Limit Electrolysis Current

Gas bubble evolution at electrochemical interfaces critically impacts electrolyzer performance and durability yet remains poorly understood at the nanoscale. Using reactive molecular dynamics at constant potential, we reveal that ion-exchange membrane proximity anchors nanobubbles on Pt nanoparticles, preventing detachment while maintaining average steady-state hydrogen evolution currents indistinguishable from those of membrane-free systems. In contrast, direct ionomer adsorption onto the catalyst results in larger reduction of the current due to active site occlusion. Anchored nanobubbles locally displace interfacial water, creating dehydrated regions at the membrane interface that can accelerate chemical degradation pathways in anion-exchange membranes. By resolving nanobubble dynamics in the 1–2 nm confinement regime inaccessible to experiments, our results demonstrate that membrane proximity governs bubble confinement without compromising efficiency, reframing it as a design parameter for durability management in electrolysis systems. These insights advance molecular-level strategies for catalyst–membrane interface engineering in hydrogen and CO₂ electrolyzers.