Operando surface-sensitive UV-Vis methods on nickel-based oxygen evolution reaction electrocatalysts
Abstract/Contents
- Abstract
- Operando surface-sensitive measurements are crucial for understanding the dynamics of the electrode surface chemistry. However, existing methods, such as adopting the meniscus-method with the ambient pressure X-ray photoelectron spectroscopy, are often inaccessible or expensive, impeding the development of advanced electrodes used in electrocatalysts and batteries. In this thesis, UV-Vis- based operando surface methods are developed to study the dynamic surface of nickel-based electrocatalysts. First, this study applies direct current-based UV-Vis spectroscopy on epitaxial lanthanum nickel oxide (LNO) to study the active surface layer for oxygen evolution reaction (OER). Through careful control of the epitaxial film thickness and terminating atomic layer, this study deconvolutes the surface UV-Vis spectrum from the bulk one and proves the active OER surface phase on Ni-terminating LNO to be a single layer of nickel (oxy)hydroxide. The lack of such a surface layer explains the poor OER activity on La-terminating LNO. Next, the thesis proposes a color impedance spectroscopy (CIS)-based technique that unlocks more accessible, lab- based operando surface measurements on a broader range of systems. The setup controls the depth of charge carriers' movement within the electrode by tuning the frequency of the applied AC signal. Theoretically, any coupled light source yields a surface-sensitive spectrum at higher AC frequencies. A physics-based transmission line impedance model for general mixed ionic-electronic conductors is built to simulate both the EIS and CIS outcome. The impedance model provides insights on EIS results analysis that is crucial for interpreting impedance data. Then, the model validates the idea through forward simulation and demonstrates that bulk kinetics strongly affects the CIS spectral outcome. Adopting nickel (oxy)hydroxide film as a model system presents how CIS turns UV-Vis spectroscopy surface-sensitive. Analysis of samples with varying thicknesses deconvolutes the spectrum and reveals a highly oxidized surface layer with strong absorptivity at redox potential (~1.4 V) and OER conditions (1.6 V vs. RHE). This study expects the CIS experiment and model analysis combination to enable a wide range of novel operando electrode surface studies.
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 | 2022; ©2022 |
| Publication date | 2022; 2022 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Liang, Yu-Lun |
|---|---|
| Degree supervisor | Chueh, William |
| Thesis advisor | Chueh, William |
| Thesis advisor | Kanan, Matthew William, 1978- |
| Thesis advisor | Moerner, W. E. (William Esco), 1953- |
| Degree committee member | Kanan, Matthew William, 1978- |
| Degree committee member | Moerner, W. E. (William Esco), 1953- |
| Associated with | Stanford University, Department of Chemistry |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Yu-Lun "Allen" Liang. |
|---|---|
| Note | Submitted to the Department of Chemistry. |
| Thesis | Thesis Ph.D. Stanford University 2022. |
| Location | https://purl.stanford.edu/cq608fs0485 |
Access conditions
- Copyright
- © 2022 by Yu-Lun Liang
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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