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

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.