Durable, pure-water-fed, anion-exchange-membrane electrolyzers through interphase engineering

Anion-exchange-membrane water electrolyzers (AEMWEs) promise scalable low-cost hydrogen production but are limited by the electrochemical instability of their anode ionomers. We report interphase engineering using inorganic-containing molecular additives that co-assemble with ionomer, enabling pure-water-fed AEMWEs to operate with a degradation rate < 0.5 mV·h⁻1 at an industry-relevant 2.0 A·cm⁻2 and 70 ℃ – a > 20-fold durability improvement. Analysis of different additives and ionomers shows that the stabilization mechanism involves crosslinks between metal oxo/hydroxo oligomers and ionomers. Under operation, the inorganic additive enriches, forming an interphase near the water-oxidation catalyst that passivates the anode ionomer against continuous degradation while maintaining mechanical integrity and hydroxide conductivity. This additive-based interphase-engineering strategy provides a path to durable AEMWEs that operate without supporting electrolytes and is adaptable across diverse catalysts and ionomers for electrochemical technologies.