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

Shih, Pei-Chieh

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https://hdl.handle.net/2142/105905 Copy

Description

Title

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

Author(s)

Shih, Pei-Chieh

Issue Date

2019-07-08

Director of Research (if dissertation) or Advisor (if thesis)

Yang, Hong

Doctoral Committee Chair(s)

Yang, Hong

Committee Member(s)

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

Department of Study

Chemical & Biomolecular Engr

Discipline

Chemical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Oxygen evolution reaction catalysts
• pyrochlore
• acid water electrolysis

Abstract

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.

Graduation Semester

2019-08

Type of Resource

text

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

Copyright and License Information

Copyright 2019 Pei-Chieh Shih

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