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O: Fachverband Oberflächenphysik

O 45: Solid-Liquid Interfaces II: Reactions and Electrochemistry

O 45.7: Vortrag

Dienstag, 17. März 2020, 12:15–12:30, WIL C107

Ab initio thermodynamics study of two-dimensional Ir and Ru oxide nanosheets as active oxygen evolution reaction catalyst in acidic media — •Po-Yuan Huang, Yonghyuk Lee, Christoph Scheurer, and Karsten Reuter — Technical University of Munich, Germany

Iridium and ruthenium oxides are among the most active oxygen evolution reaction (OER) catalysts in acidic media, with iridium oxide exhibiting somewhat lower activity, but higher durability. As one promising strand to maximize precious atom efficiency, highly active two-dimensional hexagonal nanosheets of both oxides have recently been reported [1,2]. Here, we use density-functional theory based ab initio thermodynamics to systematically compare the stable surface terminations of the isostructural Ir and Ru nanosheets as a function of the applied potential. Extending our investigation over both the sheet surface and the sheet edge, we find the Ir nanosheet to deprotonate already at much lower potentials. Thermodynamic Gibbs free energy barriers along the generally accepted OER reaction pathway are investigated to gain insight into the overpotentials and assess whether the earlier deprotonation can rationalize the different Tafel slopes measured for the two oxide nanosheets.
[1] D. Weber et al., J. Mater. Chem. A 6, 21558 (2018).
[2] S. Laha et al., Adv. Energy Mater. 9, 1803795 (2019).