Solid-state architecture for an elevated-temperature photoelectrochemical cell
Abstract/Contents
- Abstract
- Solar fuels can be utilized to overcome the storage and distribution limitations of solar energy by using sunlight to convert water into hydrogen fuel. Photoelectrochemical cells (PECs) have been investigated as a tool for solar-to-hydrogen conversion for several decades, and the majority of PECs used for solar water splitting operate near room temperature with a liquid or polymeric electrolyte. These devices are typically limited by slow kinetics and thermodynamic losses at interfaces, and have often suffered from severe stability concerns. My colleagues and I have recently shown that even a small temperature increase can substantially improve the minority carrier collection efficiency of PECs, thus increasing the photocurrent density output by the cell. Additionally, using a detailed-balance approach, we have shown that a solid-state composite device operating at 450 C could achieve solar-to-hydrogen efficiencies as high as 17%. In this dissertation, I first review our experimental work confirming enhanced water-splitting performance for modest increases in temperature up to 70 C. These enhancements are observed for multiple metal-oxide systems, including iron oxide and bismuth vanadate. I then describe how we developed a composite, solid-state architecture for elevated temperature photoelectrochemistry using an oxide-based solid electrolyte. Since the oxygen evolution reaction is typically limiting due to its catalytic complexity, most of the subsequent work focuses on this reaction at the photoanode surface. Next, I discuss the fabrication and characterization of a solid-state PEC composed of a bismuth vanadate light absorber and a yttria-stabilized zirconia thin-film solid electrolyte. Our cell design has enabled us to achieve photocurrent densities above 100 mA/cm^2 at temperatures between 300 to 400 C -- among the highest current densities observed in literature for a solid-state photoelectrochemical cell. Throughout, I highlight my work on optimizing the oxide layers, current collector morphology, and deposition techniques to improve cell performance. To better understand the results, I share our findings regarding the role of thermal effects on the observed performance, and I demonstrate my initial results for future materials of interest like titanium oxide. Ultimately, my thesis conveys the benefits of elevated temperature on PEC performance, the role of heterojunctions on enhanced charge-separation, and the opportunity provided by thin-film solid electrolytes to enable high photocurrent densities for photon-assisted oxygen evolution.
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 | 2018; ©2018 |
| Publication date | 2018; 2018 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Boloor, Madhur |
|---|---|
| Degree supervisor | Chueh, William |
| Thesis advisor | Chueh, William |
| Thesis advisor | Melosh, Nicholas A |
| Thesis advisor | Prinz, F. B |
| Degree committee member | Melosh, Nicholas A |
| Degree committee member | Prinz, F. B |
| Associated with | Stanford University, Department of Materials Science and Engineering. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Madhur Boloor. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2018. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2018 by Madhur Boloor
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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