Utilizing synchrotron X-ray diffraction and X-ray absorption spectroscopy to study materials for electrochemical reactions involving hydrogen and carbon dioxide
Abstract/Contents
- Abstract
- Developing a more sustainable energy economy would offer several benefits, including mitigation of the most devastating aspects of climate change. The hydrogen evolution reaction (HER) and electrochemical CO2 reduction (CO2R) have been proposed as ways to sustainably generate chemicals and fuels using renewable electricity. Before these reactions can be adopted on a large scale, however, electrocatalysts with higher activity and selectivity need to be developed. A lack of understanding of how the surfaces of these electrocatalysts develop during the reaction complicates the connection between the structure of these materials and their activity, making the rational design of electrocatalysts difficult. This dissertation discusses efforts to develop an improved understanding of the materials used in electrochemical reactions involving carbon dioxide and hydrogen. First, a variety of metal phosphide and sulfide materials are evaluated as electrocatalysts for CO2R. These materials were found to be highly selective for the HER over CO2R, and collaboration with computational chemists showed the need to calculate the energetics for the competing HER when predicting new catalysts for CO2R. Next, this dissertation discusses the development of an electrochemical cell which allows for the in situ characterization of electrocatalyst surfaces under operating conditions where catalyst performance is typically benchmarked. This approach uses grazing incidence X-ray diffraction (GIXRD) and grazing-incidence X-ray absorption spectroscopy (GIXAS) to characterize the top 2-3 nm of planar electrocatalysts at reaction rates in excess of -100 mA cm-2, providing insight into the active surface of the electrocatalyst under operating conditions. To extract quantitative lattice parameters from these GIXRD measurements, a model for the refraction of X-rays as they pass through the electrolyte-electrode interface was developed. Lastly, in situ XRD is utilized to study hydrogen intercalation in palladium electrodes. This process plays a role in electrocatalysis, hydrogen storage, and hydrogen-selective membranes, and understanding the formation of palladium hydride as a function of electrochemical potential could improve the design of these materials. These experiments show a clear hysteresis in the potential where hydrogen intercalates and deintercalates, showing that hydrogen intercalation and deintercalation are not microscopic reverses. This thesis has enabled a deeper understanding of how the structure of electrocatalysts and other electrode materials evolves under in situ conditions, aiding the rational design of improved materials for electrochemical reactions involving hydrogen and carbon dioxide
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2020; ©2020 |
| Publication date | 2020; 2020 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Landers, Alan Taylor |
|---|---|
| Degree supervisor | Jaramillo, Thomas Francisco |
| Thesis advisor | Jaramillo, Thomas Francisco |
| Thesis advisor | Chidsey, Christopher E. D. (Christopher Elisha Dunn) |
| Thesis advisor | Kanan, Matthew William, 1978- |
| Degree committee member | Chidsey, Christopher E. D. (Christopher Elisha Dunn) |
| Degree committee member | Kanan, Matthew William, 1978- |
| Associated with | Stanford University, Department of Chemistry. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Alan Taylor Landers |
|---|---|
| Note | Submitted to the Department of Chemistry |
| Thesis | Thesis Ph.D. Stanford University 2020 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2020 by Alan Taylor Landers
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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