Influence of surface atomic structure demonstrated on oxygen incorporation mechanism at a model perovskite oxide

M. Riva, M. Kubicek, X. Hao, G. Franceschi, S. Gerhold, M. Schmid, H. Hutter, J. Fleig, C. Franchini, B. Yildiz, U. Diebold

Institut für Angewandte Physik, Technische Universität Wien, 1040 Wien, Austria
Institute of Chemical Technologies and Analytics, TU Wien, 1060 Wien, Austria
Key Laboratory of Applied Chemistry, Department of Chemical Engineering, Yanshan University, 066004 Qinhuangdao, China
Faculty of Physics and Center for Computational Materials Science, University of Vienna,, 1090 Wien, Austria
Laboratory for Electrochemical Interfaces, Departments of Nuclear Science and Engineering, and Materials Science and Engineering, MassachusettsInstitute of Technology, Cambridge, MA 02139, U. S. A.

Nat. Commun. 9 (2018) 3710

Perovskite oxide surfaces catalyze oxygen exchange reactions that are crucial for fuel cells, electrolyzers, and thermochemical fuel synthesis. Here, by bridging the gap between surface analysis with atomic resolution and oxygen exchange kinetics measurements, we demonstrate how the exact surface atomic structure can determine the reactivity for oxygen exchange reactions on a model perovskite oxide. Two precisely controlled surface reconstructions with (4 × 1) and (2 × 5) symmetry on 0.5 wt.% Nb-doped SrTiO₃(110) were subjected to isotopically labeled oxygen exchange at 450 °C. The oxygen incorporation rate is three times higher on the (4 × 1) surface phase compared to the (2 × 5). Common models of surface reactivity based on the availability of oxygen vacancies or on the ease of electron transfer cannot account for this difference. We propose a structure-driven oxygen exchange mechanism, relying on the flexibility of the surface coordination polyhedra that transform upon dissociation of oxygen molecules.

Corresponding author: Bilge Yildiz and Ulrike Diebold (diebold).

This work was featured as Research Highlight in Nature Nanotechnology.

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