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Abstract
Perovskites exhibit outstanding performance in applications such as photocatalysis, electrochemistry, or photovoltaics, yet their practical use is hindered by the instability of these materials under operating conditions, specifically caused by the segregation of alkali cations toward the surface. The problem arises from the bulk strain related to different cation sizes, as well as the inherent electrostatic instability of perovskite surfaces. Here, we focus on atomistic details of the surface-driven process of interlayer switching of alkali atoms at the inorganic perovskite surface. We show that the (001) surface of KTaO3 cleaved at room temperature contains equally populated TaO2 and KO terminations, while the uncompensated polarity of these terminations promotes diffusion of KO from the subsurface toward the topmost surface layer at temperatures as low as 200 °C. This effect is directly probed at the atomic scale by Atomic Force Microscopy and the chemical properties of the resulting surfaces are investigated by the adsorption of CO and H2O. The experiments indicate that KO segregation is associated with the formation of K and O vacancies in the near-surface region, which is further supported by depth-dependent X-ray Photoelectron Spectroscopy measurements and Density Functional Theory calculations. Our study shows that the KO segregation influences the surface reactivity both toward CO and water, which was probed at the atomic scale.
Original language | English |
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Pages (from-to) | 70010-70019 |
Number of pages | 10 |
Journal | ACS Applied Materials and Interfaces |
Volume | 16 |
Issue number | 50 |
Early online date | 10 Dec 2024 |
DOIs | |
Publication status | Published - 18 Dec 2024 |
Austrian Fields of Science 2012
- 103018 Materials physics
- 103020 Surface physics
Keywords
- cation segregation
- KTaO3
- scanning probe microscopy
- perovskites
- solid oxide fuel cells
- ORR
- photoelectron spectroscopy
- density functional theory
- KTaO
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Dive into the research topics of 'Atomic-Scale View at the Segregation of Alkali Metals toward the KTaO3(001) Perovskite Surface'. Together they form a unique fingerprint.Projects
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TACO: Taming Complexity in Materials Modeling
Diebold, U., Kresse, G., Mezger-Backus, E. H. G., Dellago, C. & Franchini, C.
1/03/21 → 28/02/29
Project: Research funding