Hydrophilic Graphene Oxide‐Modified Composite Diaphragm for High‐Efficiency Alkaline Water Electrolysis

ABSTRACT The integration of intermittent renewable energy with alkaline water electrolysis (AWE) for green hydrogen production has emerged as a critical technological trend. However, conventional hydrophobic polyphenylene sulfide (PPS) diaphragms suffer from high ionic resistance and excessive gas crossover under low/variable load operations and rapid start‐stop cycles, leading to elevated energy consumption and critical safety risks. Herein, we engineered a hydrophilic graphene oxide (GO)‐modified composite diaphragm via a scalable one‐step phase inversion casting process. The composite diaphragm integrates a robust PPS fabric support with a functional layer comprising polysulfone (PSU), zirconia (ZrO 2 ) nanoparticles, polyvinylpyrrolidone (PVP), and GO. The synergistic interaction between GO nanosheets and PVP enhances hydrophilicity, optimizes pore architecture, and improves gas‐blocking performance. The resulting diaphragm demonstrates an ultralow area resistance of 0.11 Ω·cm 2 and an elevated bubble point pressure of 2 bar. At 2 V, the PVP/GO‐modified composite diaphragm reached 600 mA cm −2 . It demonstrated stability over 200 h at 80°C in 30 wt% KOH under 300 mA cm −2 constant current. This work provides a scalable and efficient strategy for designing high‐performance diaphragms that harmonize hydrophilicity, ionic conductivity, and gas‐blocking capabilities, demonstrating significant potential for efficient hydrogen production.