Plasma-Engineered Polyethylene-Reinforced Anion Exchange Membranes With Low Ionic Resistance and Low Hydrogen Crossover for Water Electrolysis.

Anion exchange membrane water electrolysis (AEMWE) enables low-cost green hydrogen production but remains limited by the delicate balance among ionic resistance, gas crossover, and mechanical durability in hydrocarbon-based membranes. Although reinforced composite membranes (RCMs) alleviate this limitation, conventional expanded polytetrafluoroethylene (ePTFE) reinforcements suffer from fluorocarbon-hydrocarbon interfacial incompatibility, resulting in incomplete ionomer impregnation. We report a plasma-modified polyethylene (PE) reinforcement that promotes hydrocarbon ionomer infiltration within dense submicron pores. Oxygen plasma treatment introduces polar functional groups on the PE surface, enhancing wettability and capillary-driven impregnation without altering morphology. The plasma-treated PE-based RCM achieves high strength, low swelling, and reduced hydrogen crossover, exhibiting a crossover current density of 0.133 mA cm-2 at ∼30 µm thickness, over fourfold lower than a non-reinforced membrane. Under practical operation, the anode hydrogen concentration remains well below the explosion safety limit, while the AEMWE performance is comparable to an optimized alcohol-mediated PTFE-based RCM, despite its denser pore structure. A membrane selectivity factor coupling ohmic resistance and hydrogen crossover quantifies this balance. The plasma-treated PE-based RCM exhibits the highest membrane selectivity factor, 3.26- and 2.26-fold higher than the non-reinforced and ePTFE-reinforced membranes, respectively. Continuous operation for 1000 h at 1.0 A cm-2 confirms long-term durability.