Rationalizing the Effect of Oxygen Vacancy on Oxygen Electrocatalysis in Li–O2 Battery. Issue 24 (20th May 2020)

• Record Type: Journal Article
• Authors: Li, Jiabao; Shu, Chaozhu; Liu, Chunhai; Chen, Xianfei; Hu, Anjun; Long, Jianping
• Is Part Of: Small. Volume 16:Issue 24(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-05-20
• Subjects: electrocatalysts -- Li–O2 batteries -- magnetron sputtering -- oxygen electrodes -- oxygen vacancies; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202001812
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: 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 NiCo2 O4 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 ( E f ), which provides extra electronic state around E f, 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 Li2 O2, leading to poor catalytic activity for oxygen evolution reaction (OER). Abstract : 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.