Regulating lattice oxygen participation through Ta-enabled high-entropy engineering for durable acidic oxygen evolution.

Developing acidic oxygen evolution reaction (OER) catalysts with both high activity and high durability is essential for implementing a proton exchange membrane water electrolyzer (PEMWE) in sustainable hydrogen production. However, achieving efficient lattice oxygen activation while maintaining structural robustness during acidic OER remains a fundamental challenge due to the intrinsic activity-stability trade-off associated with lattice oxygen participation. Herein, we report a robust RuMnCoNiTa-O high-entropy oxide catalyst enabled by Ta-mediated electronic regulation and entropy-stabilized local coordination engineering. The optimized catalyst delivers a low overpotential of 196 mV at 10 mA cm-2 together with outstanding durability exceeding 500 h under acidic conditions, substantially outperforming commercial RuO2. Operando spectroscopic investigations combined with Ru dissolution analysis reveal that the Ta-enabled high-entropy structure promotes lattice oxygen participation while mitigating structural degradation and Ru dissolution during the OER. When employed as the anode catalyst in a membrane electrode assembly (MEA), it delivers stable operation for over 280 h at 200 mA cm-2, verifying its practical potential for hydrogen production. This work demonstrates that rational regulation of the local coordination and electronic environment can decouple lattice oxygen activation from catalyst instability, providing an effective strategy for overcoming the activity-stability trade-off in acidic OER catalysis.