Composite membranes with tailored interfaces for high-efficiency anion exchange membrane-based alkaline water and simulated alkaline seawater electrolysis

Hydrogen production via water electrolysis is considered a cornerstone technology for building a sustainable and carbon-free energy system. However, current electrolysis technologies face critical membrane-related issues, especially in seawater environments, such as high ionic resistance, poor mechanical properties, and low selectivity towards chlorides. Here, we develop a reinforced composite membrane (RCM) featuring a chloride-blocking surface layer and PTFE support. The RCM exhibits low Cl⁻ permeability (1.03 × 10⁻⁶ cm² s⁻¹), over ten times lower than commercial membranes, while maintaining high hydroxide conductivity (118.03 mS cm⁻¹) and low swelling (3.52%). It delivers excellent performance in both anion exchange membrane water electrolysis (AEMWE) and asymmetrically fed seawater electrolysis (SWE), achieving 1.68 V at 1 A cm⁻² (80 °C) in AEMWE and exceptional Cl⁻/OH⁻ selectivity in SWE. Long-term operation tests show negligible performance degradation over 500 hours under both operation conditions. To the best of our knowledge, this is the first report of a membrane specifically engineered for asymmetrically fed SWE, addressing the critical challenges of chloride crossover and membrane deformation. Furthermore, the RCM's high dimensional stability and facile fabrication conditions enable scalable integration with functional nanomaterials (e.g., NiFe-LDHs, rGO and Pt/C NPs), while minimizing the risk of nanoparticle detachment. This work establishes a versatile membrane design framework for advanced electrolysis systems and potential applications in related fields.