Activating valence oscillations in reconstructed high-entropy selenide for self-stabilized seawater oxidation through...

Lattice oxygen redox (LOR) provides a compelling avenue to boost the oxygen evolution reaction by circumventing the scaling relationship of oxygen intermediates. However, its intrinsic oxidative pathway inevitably accelerates structural degradation, especially in aggressive seawater. Herein, we present a unique localized LOR buffering strategy to overcome the abovementioned activity-stability trade-off using interstitial boron-doped high-entropy selenide as a model electrocatalyst. Combined experimental and theoretical investigations demonstrate that interstitial boron crucially promotes localized LOR within the reconstructed oxyhydroxide layer, which triggers dynamic, quasi-reversible valence oscillations in adjacent Ni centers. This adaptive electron exchange effectively mitigates the irreversible over-oxidation and dissolution of the active sites while strengthening metal-oxygen covalency for continuous site regeneration. Concurrently, the selectively formed stronger B-Co-Se covalent framework, along with the rapid formation of chloride-repelling selenate layers, further preserves the lattice against corrosive attack. Thus, the catalyst sustains >1000 h of stable operation at 500 mA cm^-2 with its overpotential remarkably decreasing by 180 mV in alkaline seawater. This work establishes a transferable valence-adaptation strategy for designing self-stabilizing electrocatalysts in extreme electrolytic environments.