Abstract
Oxygen evolution reaction (OER) is a kinetic bottleneck in water electrolysis. Activating lattice oxygen oxidation mechanism (LOM) can break the limitation of the theoretical overpotential of the traditional adsorbate evolution mechanism (AEM) and improve the intrinsic activity. Here, we introduced Ag single atoms and Se vacancies in CoSe2 (Ag-CoSe2), and found that Ag single atoms and Se vacancies could activate lattice oxygen in CoOOH electrochemically in-situ derived from CoSe2, triggering the LOM. The catalyst exhibits a low overpotential of 167 mV@10 mA cm−2 and a high mass activity of 732.925 A g−1@250 mV. More importantly, the Ag-CoSe2||Pt/C pair requires only 1.68 V to deliver 500 mA cm−2 in an anion-exchange membrane electrolyzer (30 wt% KOH, 60℃) and maintains virtually no degradation for up to 1500 h. Advanced spectroscopic analyses and density-functional theory calculations demonstrate that the synergy between Ag single atoms and Se vacancies results in an upward shift in the O 2p band and strengthens the covalency of metal-oxygen bonds. This effect activates the lattice oxygen oxidation mechanism and reduces the adsorption energy barrier. Additionally, the shortened Co-Se bond and the decreased formation energy of Se vacancies contribute to enhanced structural and catalytic stability in CoSe₂.
Published Version
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