Pathway Engineering Enables Durable Iridium‐Free Acidic Water Oxidation

The pursuit of noble metal‐free alternatives to iridium for the acidic oxygen evolution reaction (OER) is critically impeded by a pervasive activity‐stability trade‐off, wherein non‐precious metals undergo rapid oxidative dissolution under operating potentials. Here, we report a lutetium‐stabilized cobalt oxide catalyst (Lu 0.08 Co 2.92 O 4 ) designed through site‐specific electronic modulation, achieving a synergistic enhancement of both activity and stability in acidic OER for proton exchange membrane water electrolyzers (PEMWEs). Operando spectroscopies combined with theoretical simulations reveal that Lu incorporation introduces robust Lu‐O bonds and induces charge redistribution that strengthens Co‐O covalency and suppresses Co 2+ dissolution, which is critical for improved OER durability, and simultaneously optimizes the Co‐Co distance to favor direct O‐O radical coupling with a reduced energy barrier. Leveraging these structural advantages, a practical PEMWE employing Lu 0.08 Co 2.92 O 4 delivers an industrially relevant current density of 1000 mA cm −2 at 1.837 V. Separately, it maintains stable operation for over 900 h under a stepwise current density from 200 to 500 mA cm −2 , highlighting its potential for sustainable hydrogen production.