Theory‐Guided Design of Ru–NiFe Cathode Catalysts for Anion Exchange Membrane Water Electrolysis at Large Electrode Scale

ABSTRACT A significant gap persists between advanced catalyst synthesis in laboratories and the industrial requirements for water electrolysis. The key challenge lies in simultaneously achieving electrode scalability, high catalytic activity, and long‐term stability. Through theoretical simulation screening, we synthesized a free‐standing cathode catalyst composed of Ru clusters anchored on a Ni x Fe y OOH substrate via Ru─O─Ni/Fe bridges. Advanced characterizations and theoretical calculations reveal that the Ru–NiFe catalyst achieves efficient catalytic activity due to Ru─O─Ni/Fe bridges, fine‐tuning the electronic structure and enhancing catalytic energetics, while Ru cluster introduction increases the number of active sites and modulates hydrogen intermediate adsorption/desorption strength. The as‐prepared Ru–NiFe electrocatalyst for the hydrogen evolution reaction delivers ultralow overpotentials of 5 mV at 10 mA cm − 2 and maintains stable operation at 500 mA cm − 2 for over 1000 h. A large‐scale (19 × 19 cm 2 ) anion‐exchange‐membrane water electrolyzer (AEM–WE) based on Ru–NiFe shows a low cell voltage of 2.98 V at 10 A and stable operation for 2800 h. This study provides valuable insights into designing large‐area electrodes with high activity, long‐term stability, and scalable production for industrial AEM–WE applications.