Rationalizing the Effect of Oxygen Vacancy on Oxygen Electrocatalysis in Li–O2 Battery

Albeit the effectiveness of surface oxygen vacancy in improving oxygen redox reactions in Li–O2 battery, the underpinning reason behind this improvement remains ambiguous. Herein, the concentration of oxygen vacancy in spinel NiCo2O4 is first regulated via magnetron sputtering and its relationship w...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2020-06, Vol.16 (24), p.e2001812-n/a
Main Authors: Li, Jiabao, Shu, Chaozhu, Liu, Chunhai, Chen, Xianfei, Hu, Anjun, Long, Jianping
Format: Article
Language:English
Subjects:
Catalytic activity
Charge transfer
Crystal structure
Density functional theory
electrocatalysts
Electron states
Li–O2 batteries
Magnetron sputtering
Nanotechnology
oxygen electrodes
Oxygen evolution reactions
oxygen vacancies
Redox reactions
Vacancies
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Summary:Albeit the effectiveness of surface oxygen vacancy in improving oxygen redox reactions in Li–O2 battery, the underpinning reason behind this improvement remains ambiguous. Herein, the concentration of oxygen vacancy in spinel NiCo2O4 is first regulated via magnetron sputtering and its relationship with catalytic activity is comprehensively studied in Li–O2 battery based on experiment and density functional theory (DFT) calculation. The positive effect posed by oxygen vacancy originates from the up shifted antibond orbital relative to Fermi level (Ef), which provides extra electronic state around Ef, eventually enhancing oxygen adsorption and charge transfer during oxygen redox reactions. However, with excessive oxygen vacancy, the negative effect emerges because the metal ions are mostly reduced to low valence based on the electrical neutral principle, which not only destabilizes the crystal structure but also weakens the ability to capture electrons from the antibond orbit of Li2O2, leading to poor catalytic activity for oxygen evolution reaction (OER). By adjusting the center position of the d band relative to the Fermi level, the oxygen vacancy generated by magnetron sputtering can not only adjust the filling of the antibonding orbit to enhance the adsorption of oxygen, but also optimize the number of eg electrons to accelerate oxygen evolution reaction (OER) dynamics.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.202001812