Surface decorations on mixed ionic and electronic conductors: effects on surface potential, defects, and the oxygen exchange kinetics
Author(s)
Type
Journal Article
Abstract
The oxygen exchange kinetics of epitaxial Pr0.1Ce0.9O2−δ electrodes was modified by decoration with submonolayer amounts of different basic (SrO, CaO) and acidic (SnO2, TiO2) binary oxides. The oxygen exchange reaction (OER) rate and the total conductivity were measured by in situ PLD impedance spectroscopy (i-PLD), which allows to directly track changes of electrochemical properties after each deposited pulse of surface decoration. The surface chemistry of the electrodes was investigated by near-ambient pressure XPS measurements (NAP-XPS) at elevated temperatures and by low-energy ion scattering (LEIS). While a significant alteration of the OER rate was observed after decoration with binary oxides, the pO2 dependence of the surface exchange resistance and its activation energy were not affected, suggesting that surface decorations do not alter the fundamental OER mechanism. Furthermore, the total conductivity of the thin films does not change upon decoration, indicating that defect concentration changes are limited to the surface layer. This is confirmed by NAP-XPS measurements which find only minor changes of the Pr-oxidation state upon decoration. NAP-XPS was further employed to investigate changes of the surface potential step on decorated surfaces. From a mechanistic point of view, our results indicate a correlation between the surface potential and the altered oxygen exchange activity. Oxidic decorations induce a surface charge which depends on their acidity (acidic oxides lead to a negative surface charge), affecting surface defect concentrations, any existing surface potential step, potentially adsorption dynamics, and consequently also the OER kinetics.
Date Issued
2023-06-07
Date Acceptance
2023-05-01
Citation
ACS Applied Materials and Interfaces, 2023, 15 (22), pp.26787-26798
ISSN
1944-8244
Publisher
American Chemical Society
Start Page
26787
End Page
26798
Journal / Book Title
ACS Applied Materials and Interfaces
Volume
15
Issue
22
Copyright Statement
Copyright © 2023 The Authors. Published by American Chemical Society. This publication is licensed under
CC-BY 4.0.
CC-BY 4.0.
License URL
Identifier
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:001014368800001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=a2bf6146997ec60c407a63945d4e92bb
Subjects
CAPACITANCE
CATHODES
CONDUCTIVITY
defect chemistry
ELECTROCHEMICAL PROPERTIES
IMPROVEMENT
Materials Science
Materials Science, Multidisciplinary
mixed ionic electronic conductors
MODEL
Nanoscience & Nanotechnology
NONSTOICHIOMETRY
OXIDE
oxygenexchange
PEROVSKITE THIN-FILMS
pulsed laser deposition
REDUCTION
Science & Technology
Science & Technology - Other Topics
surface decoration
surface potential
Technology
Publication Status
Published
Date Publish Online
2023-05-22