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© 2015 American Chemical Society.Nanostructured MnO2 is renowned for its excellent energy storage capability and high catalytic activity. While the electronic and structural properties of MnO2 surfaces have received significant attention, the properties of the grain boundaries (GBs) and their contribution to the electrochemical performance of the material remains unknown. Through density functional theory (DFT) calculations, the structure and electronic properties of the β-MnO2 ∑ 5(210)/[001] GB are studied. Our calculations show this low energy GB has a significantly reduced band gap compared to the pristine material and that the formation of oxygen vacancies produces spin-polarized states that further reduce the band gap. Calculated formation energies of oxygen vacancy defects and Mn reduction at the GB core are all lower than the equivalent bulk value and in some cases lower than values recently calculated for β-MnO2 surfaces. Oxygen vacancy formation is also shown to produce a metallic behavior at the GB with defect charge distributed over a number of oxygen and manganese sites. The low energies of oxygen defect formation and the potential creation of conductive GB pathways are likely to be important to the electrochemical performance of β-MnO2.
Author(s): Dawson JA, Chen H, Tanaka I
Publication type: Article
Publication status: Published
Journal: ACS Applied Materials and Interfaces
Year: 2015
Volume: 7
Issue: 3
Pages: 1726-1734
Print publication date: 28/01/2015
Online publication date: 15/01/2015
Acceptance date: 06/01/2015
ISSN (print): 1944-8244
ISSN (electronic): 1944-8252
Publisher: American Chemical Society
URL: https://doi.org/10.1021/am507273c
DOI: 10.1021/am507273c
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