Atomic-Scale View at the Segregation of Alkali Metals toward the KTaO₃(001) Perovskite Surface

Autor(en)

Aji Alexander, Michele Reticcioli, Llorenç Albons, Jesús Redondo, Marco Corrias, Igor Píš, Zhichang Wang, Viktor Johánek, Josef Mysliveček, Cesare Franchini, Dominik Wrana, Martin Setvin

Abstrakt

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.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

Charles University Prague, University of the Basque Country, Consiglio Nazionale delle Ricerche, Peking University, Università di Bologna, Jagiellonian University in Krakow

Journal

ACS Applied Materials and Interfaces

Band

16

Seiten

70010-70019

Anzahl der Seiten

10

ISSN

1944-8244

DOI

https://doi.org/10.1021/acsami.4c13795

Publikationsdatum

12-2024

Peer-reviewed

Ja

ÖFOS 2012

103018 Materialphysik, 103020 Oberflächenphysik

Schlagwörter

ASJC Scopus Sachgebiete

Allgemeine Materialwissenschaften

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/109b5a6a-9da5-457e-b9dc-2c7e4f2f1e69