Asymmetric interface engineering boosts acidic oxygen evolution activity and stability of cobalt oxide

The acidic oxygen evolution reaction (OER) is constrained by an activity–stability trade-off: AEM is often kinetically limited, whereas enhanced lattice-oxygen participation can accelerate OER but may induce oxygen-vacancy accumulation, structural degradation, and metal dissolution. Here, we introduce an asymmetric interface strategy to regulate the relative contributions of adsorbate- and lattice-oxygen-mediated pathways. Using carbon-coated spinel Co₃O₄@C as a model system, the asymmetric Co₃O₄|C interface delivers overpotentials of 289 mV at 10 mA cm⁻² and 368 mV at 100 mA cm⁻², while sustaining 240 h operation at 100 mA cm⁻² with only a 45 mV increase in overpotential. In situ potential-dependent Co K-edge XAFS reveals moderated Co oxidation and stabilized Co–O coordination under anodic polarization. Combined in situ spectroscopy and isotope-labeled DEMS indicate a potential-dependent evolution toward an AEM-led but LOM-compatible regime at high anodic bias. DFT calculations further show that the interface raises the oxygen-vacancy formation energy and reshapes oxygenated-intermediate energetics, suppressing excessive lattice-oxygen extraction while favoring adsorbate-mediated turnover. This work establishes asymmetric interfacial electronic regulation as a generalizable strategy for balancing activity and stability in acidic OER.