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Oxygen reactivity12/24/2023 Therefore, current research efforts are mainly directed to optimize the pathway of acid-base nucleophilic attack and overcome the limitation from such LSR for developing practical electrocatalysts.Īctivating lattice oxygen to generate spin-characteristic ligand holes can tune the lattice oxygen reactivity that links to energy barrier symmetry between O–H bond cleavage and *OOH formation. For the latter, it is not subject to such LSR constraint, but the specific catalytic structural motif to trigger O–O direct coupling is difficult to realize for most catalytic materials 7, 8, 9. One implication of the above LSR is that the key steps of O–H bond cleavage and *OOH formation are mutually competing, rendering a minimum theoretical overpotential of ~0.4 eV even for the best possible material 5, 6. For the former, there is an inherent linear scaling relation (LSR) between the adsorption energy of *OOH and *OH intermediates. Regardless of which OER mechanism is applicable on a catalyst surface, it has been reported that O–O bond formation can follow two different pathways, i.e., acid-base nucleophilic attack and O–O direct coupling 7, 8. Considering the origin of O 2 product, there are two widely accepted OER mechanisms including adsorbate evolution mechanism and lattice oxygen oxidation mechanism 5, 7. The oxygen evolution reaction (OER) is a key reaction and constitutes the bottleneck in many energy conversion and storage systems such as water electrolyzers, rechargeable metal-air batteries and regenerative fuel cells 1, 2, 3, due to its intrinsically sluggish kinetics 2, 4, 5, 6. This work provides a new rational recipe to develop highly efficient catalyst towards water oxidation or other oxidative reactions through tuning lattice oxygen reactivity and scaling relation. Combining in situ spectroscopy-based characterization with first-principles calculations, we demonstrate that an intermediate level of Na + mediation (NaMn 3O 7) exhibits the optimum oxygen evolution activity. On the other hand, the presence of Na + could have specific noncovalent interaction with pendant oxygen in *OOH to overcome the limitation from linear scaling relation, reducing the overpotential ceiling. ![]() Specifically, the number of Na + is linked with lattice oxygen reactivity, which is determined by the number of oxygen hole in oxygen lone-pair states formed by native Mn vacancies, governing the barrier symmetry between O–H bond cleavage and O–O bond formation. Herein, using modeled Na xMn 3O 7 materials, we report an effective strategy to construct better oxygen evolution electrocatalyst through tuning both lattice oxygen reactivity and scaling relation via alkali metal ion mediation. However, the inherent linear scaling relation for most catalytic materials imposes a theoretical overpotential ceiling, limiting the development of efficient electrocatalysts. ![]() Developing efficient and low-cost electrocatalysts for oxygen evolution reaction is crucial in realizing practical energy systems for sustainable fuel production and energy storage from renewable energy sources.
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