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 (Lu0.08Co2.92O4) 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 Co2+ 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 Lu0.08Co2.92O4 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.