First principles modeling of the electrochemical oxygen evolution reaction : from electronic structure to kinetics
Abstract/Contents
- Abstract
- The efficient storage of intermittent, renewable energy in the form of chemical bonds is critical to successfully transition away from fossil-derived fuels and chemicals. The oxygen evolution reaction (OER) plays a central role in many of these storage technologies by splitting water molecules to supply reactive protons and electrons. The activity of OER electrocatalysts directly influences the efficiency of these technologies by reducing the overpotential required to achieve reasonable production rates. Density functional theory (DFT) is a useful tool for investigating potential OER catalyst active sites at the atomic scale in an effort to either explain experimental observation or suggest new experiments to perform. Such theoretical studies are popular for a variety of electrochemical and thermochemical reactions, but OER catalysts are particularly challenging to model because of the highly oxidizing conditions at which they operate, leading to corrosion via oxidation and dissolution of the catalyst surface. In the first part of this thesis, we examine two state-of-the-art OER catalysts, SrIrO3 and RuO2, that are known experimentally to dissolve under reaction conditions and use DFT to explore possible active sites that might form. In the case of SrIrO3 we consider various Sr-deficient surface structures, while for RuO2 we consider defect motifs such as Ru-vacancies, steps, and kinks, and in both cases we identify sites with higher theoretical activities than the ideal, defect-free surfaces. These studies are computationally expensive because they require individually probing the activity of possible active sites by calculating the stability of OER intermediates OH*, O*, and OOH* at each site. Towards circumventing these calculations, we identify an electronic structural descriptor, namely the average 2p-state energy of adsorbed atomic oxygen, that correlates strongly with the theoretical OER activity and allows for screening multiple active sites at once with a single DFT calculation. In the second part of this thesis, we attempt to move beyond the conventional thermodynamic analysis of theoretical OER activity with microkinetic modeling, which allows for a more direct comparison to experimental results. This involves explicitly modeling the aqueous-solid electrochemical interface and computing kinetic barrier heights for reactions that involve charge transfer across the interface. We find that the intrinsic barrier height for one elementary step in particular, OOH* formation, is significantly higher than the others for rutile (110) surfaces and directly accounts for the non-negligible OER overpotential observed experimentally. The resultant microkinetic model, which assumes OOH* formation to be the sole rate determining step, is analyzed in the context of experimental observations including Tafel behavior and is used to construct an OER volcano consisting solely of experimental data.
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 | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Dickens, Colin Forest |
|---|---|
| Degree supervisor | Jaramillo, Thomas Francisco |
| Degree supervisor | Noerskov, Jens |
| Thesis advisor | Jaramillo, Thomas Francisco |
| Thesis advisor | Noerskov, Jens |
| Thesis advisor | Qin, Jian, (Professor of Chemical Engineering) |
| Degree committee member | Qin, Jian, (Professor of Chemical Engineering) |
| Associated with | Stanford University, Department of Chemical Engineering. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Colin Forest Dickens. |
|---|---|
| Note | Submitted to the Department of Chemical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Colin Forest Dickens
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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