• • Ov-HE-LDHs achieve an overpotential of 210 mV at 10 mA cm−2 in 1.0 M KOH, outperforming pristine HE-LDHs (315 mV) and commercial IrO2 (330 mV), indicating a 33% reduction in overpotential relative to IrO2, which is critical for reducing energy consumption in industrial water electrolysis.
• • The catalyst sustains stable operation for 500 hours at a high current density of ~200 mA cm−2, demonstrating exceptional durability that addresses the activity-stability trade-off typical of LOM-based catalysts, essential for long-term industrial deployment.
• • XAFS analysis confirms lower metal valence states, evidencing oxygen vacancy formation, while isotope labeling and in-situ Raman spectroscopy validate the activation of the LOM pathway, providing mechanistic proof of the shift from AEM to LOM.
• • DFT calculations reveal that oxygen vacancies shift the O 2p band closer to the Fermi level, reducing the reaction energy barrier, which explains the enhanced intrinsic activity and offers a design principle for high-entropy electrocatalysts.