Stabilizing Ru Sites via Lattice Oxygen Locking of Nb‐Ru/RuO 2 to Break the Activity–Stability Trade‐Off for Acidic Oxygen Evolution

ABSTRACT Developing highly active and stable Ru‐based catalysts for the acidic oxygen evolution reaction (OER) is essential to accelerate the industrialization of proton exchange membrane water electrolysis (PEMWE). However, Ru‐based catalysts inevitably follow the lattice oxygen mechanism (LOM) during the actual reaction, which in turn triggers severe Ru dissolution. While shifting the reaction pathway to the adsorbate evolution mechanism (AEM) improves stability, it often compromises catalytic activity. Herein, we design an Nb‐doped Ru/RuO 2 heterostructure catalyst to inhibit the unstable LOM, and concurrently propose a favorable Brønsted Site‐Promoted Proton Transfer (BSPT) mechanism derived from the AEM. Specifically, the synergy between Nb doping and Ru/RuO 2 heterostructure enhances activity by improving deprotonation capability and optimizing oxygen‐intermediate adsorption, while simultaneously improving durability by stabilizing lattice oxygen and suppressing excessive oxidation and dissolution of Ru. Consequently, the Nb‐Ru/RuO 2 delivers an overpotential of 186 mV at 10 mA cm −2 with impressive durability over 3000 h. In a working PEMWE, it exhibits remarkable durability for 3000, 1200, and 900 h at 500, 1000, and 2000 mA cm −2 . This study offers novel design principles and theoretical foundations to advance efficient, low‐cost PEMWE hydrogen production.