Overcoming the Activity-Stability Trade-Off in Electrocatalysts via Unconventional Two-Step Structural...

The activation of lattice oxygen in oxide catalysts via structural reconstruction is critical for optimizing the catalytic performance in oxidation-reduction systems. However, in electrochemical O₂ evolution, the structural transformations preceding electrochemical reconstruction and their impact on the resulting structural inhomogeneity have long remained insufficiently understood. Here, we activate the lattice oxygen of the W-doped Co-Fe amorphous oxide through spontaneous and electrochemical bulk reconstructions. Chemical state evolution studies reveal that the reconstructed active γ-layered double hydroxide (LDH), characterized by local structural inhomogeneity, promotes the formation of reactive nonbonding oxygen states, achieving Co³⁺-catalyzed O₂ evolution. The catalyst demonstrates a cell voltage of 1.69 V at 1 A cm^-2 with stable operation for 600 h in anion-exchange membrane water electrolyzers. Using in situ spectroscopic techniques, we establish dynamic correlations among Co ion oxidation states, phase structure, and lattice oxygen activation during reconstruction. Notably, we provide the first experimental evidence of a potential-dependent mechanistic transition governing both the activity and the stability of the catalyst. These findings deepen our understanding of structure-performance relationships in electrocatalysts and highlight the pivotal role of the chemical state evolution in catalytic processes.