Thermochemically synthesized separator electrode assembly with Ni/ZrO₂ catalysts for high-performance alkaline water electrolysis

Alkaline water electrolysis (AWE) is a mature and cost-effective technology for green hydrogen production; however, its performance and scalability remain constrained by the high cost and limited activity of conventional Raney Ni and NiFe electrodes, as well as Zirfon® separators. Here, we report an asymmetric separator-electrode assembly (SEA) fabricated via a scalable co-casting process, in which a Ni/ZrO₂ catalyst layer and a ZrO₂/polysulfone separator are sequentially blade coated on opposite sides to form an integrated and scalable architecture. Ni/ZrO₂ catalysts synthesized through a citric acid-assisted chelation–impregnation strategy exhibit enhanced metal-support interactions and improved catalytic activity. The optimized and in situ activated SEA delivers a current density of 1.0 A cm⁻² at 1.8 V in an Fe-containing alkaline electrolyte, meeting the U.S. Department of Energy (DOE) 2026 target while employing only cost-effective Ni foam electrodes. The SEA effectively suppresses gas crossover and exhibits negligible degradation, with a mass loss below 0.5 wt% during operation. This work demonstrates a scalable and economically viable pathway toward high-performance AWE systems by integrating the catalyst and separator into a single, unified structure.