High-throughput characterization of surface oxygen exchange kinetics in combinatorial oxide thin films

The development of more efficient fuel and electrolysis cells depends heavily on the optimization of electrode material properties. As these properties (e.g., surface catalytic activity, ionic conductivity, and electronic conductivity) can exhibit complex and dissimilar dependences on composition, it is necessary to develop methods to expedite the characterization of these materials with respect to composition. These electrodes provide catalytic activity for various half-cell reactions involving gas-phase species, and the kinetics of those reactions significantly influence the efficiency of the host device. In this work, a method leveraging combinatorial oxide thin films to simultaneously analyze the surface oxygen exchange kinetics in a series of transition-metal-substituted strontium titanate compositions is explored. Two-dimensional optical transmission relaxation (2D-OTR) is a spatially resolved extension of an existing one-dimensional technique that correlates time-dependent defect chemistry with variations in intensity of light transmitted through a combinatorial thin film. In this work a new 2D-OTR setup was constructed and applied to test the spatial variance of surface exchange coefficient (k) across combinatorial library films grown by pulsed laser deposition. The method developed for depositing these films worked relatively well, with consistent thickness, a reasonable composition gradient, and defined masked areas. However, the functionality of these films for optical experiments is in question, as they appear to age at a much faster rate than films deposited in a normal manner. This outcome may be due to the longer time spent at high temperature during combinatorial deposition compared to the growth times of homogeneous films. Going forward, it will be necessary to test more films made using the method described in this work, and adjustments may need to be made to address the issue of rapid aging.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Materials Science & Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Armstrong, Micah

Contributors dc:contributor

• Perry, Nicola H

• oxide thin films
• fuel cells

Statement dc:rights

• Copyright 2022 Micah Armstrong

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115747

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115747