Development of new pyrochlore-type electrocatalysts for oxygen evolution reaction in acid

A major challenge for the commercialization of water electrolyzer using proton exchange membrane (PEM) is the development of acid-stable, active catalysts for the oxygen evolution reaction (OER). In addition to discovering new catalysts, a fundamental understanding of OER activity and stability origin is also critical. This dissertation focuses on: (1) identifying active and acid-stable OER catalysts in comparison to the state-of-the-art RuO2 and IrO2 catalysts; (2) studying the intrinsic material properties that yield high OER activity and stability; and (3) developing synthetic techniques to enhance the OER activity of a catalyst. The first part of the thesis concentrates on new material synthesis and methods to analyze activity and stability. Next, both theoretical calculations and experimental analysis are used to study the material properties. The last part discusses approaches that lead to high surface area and enhanced catalytic performance. Specifically, pyrochlore-type ruthenium (Ru) and iridium (Ir) based catalysts were synthesized and characterized for their OER performance. Introducing yttrium (Y) in these pyrochlores increased the overall activity and stability. To explain this behavior, X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations were used to study the electronic and structural properties of these materials. Additionally, a range of iridium-based pyrochlores with lanthanide (La) series metals were studied to identify the important effects of the A-site metal atoms on the OER catalytic properties. To synthesize high surface area, porous yttrium ruthenate pyrochlores, two techniques were utilized: polymeric entrapment synthesis and acid porogen strategy. The polymeric entrapment reduced the synthesis temperature, whereas the addition of perchloric acid generated pores during our established sol-gel synthesis. These materials showed enhanced OER activity, attributed to higher surface area. The results in this dissertation provide new insights towards the design and development of active and stable OER catalysts.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2019

Author dc:creator

• Shih, Pei-Chieh

Contributors dc:contributor

• Yang, Hong
• Diao, Ying
• Flaherty, David W.
• Braun, Paul V.

• Oxygen evolution reaction catalysts
• pyrochlore
• acid water electrolysis

Statement dc:rights

• Copyright 2019 Pei-Chieh Shih

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/105905

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/105905