Scalable Sol–Gel NiFe (Oxy)hydroxide Coatings on Ni Foam Yield Unified Anodes for Robust AEM Water Electrolyzer Modules

NiFe-based catalysts are promising for the oxygen evolution reaction in anion exchange membrane water electrolyzers, but durability and porous transport layer (PTL) corrosion remain major challenges. Here, we report a scalable sol–gel method to integrate NiFe (oxy)hydroxide directly onto Ni foam, eliminating external PTL exposure and the need for ionomer additives that accelerate degradation. Unlike electrodeposition, the sol–gel approach ensures a uniform, conformal coating over the entire substrate with controlled thickness. Double-coated electrodes achieve a current density of 3.5 A cm–2 at 1.9 V with minimal decay over 300 h, outperforming commercial NiFe catalysts. Electrochemical analysis reveals that the integrated architecture enhances both activity and durability, as evidenced by low Tafel slopes (22 mV dec–1) and reduced charge transfer resistance at high current densities. This integrated design retains the foam’s porous structure for efficient mass transport and obviates the need for precious metal coatings, reducing costs. The robust, multilayer sol–gel strategy provides a scalable route to durable, high-performance anodes, advancing cost-effective hydrogen production and enabling large-scale water electrolysis systems for clean energy applications.