Ionics at nanoscale : application to fuel cells
Abstract/Contents
- Abstract
- The overall efficiency of energy conversion devices such as batteries, fuel cells, and biological cells is often limited by charge transfer reactions at electrode-electrolyte interfaces. Because interfaces are the site of nearly all chemical (and electrochemical) reactions, understanding and improving their characteristics and structures can lead to significant reductions in both catalytic and interfacial losses. To this end, nano electrochemistry may offer us ways to understand details of charge transfer reaction at nanoscale resolution and open opportunities to engineer the interface with better kinetics. This work presents the results of three studies aimed at lowering the elec- trochemical reaction losses in both ceramic fuel cells and biological systems. The first part of work discusses a study of oxide ion incorporation and transport at the cathode of solid oxide fuel cells (SOFC). SOFCs are an attractive clean en- ergy technology because of the low to zero emissions from their operation and their potentially high efficiency. For wider applications, it is desirable to lower the oper- ation temperature of SOFCs, but this causes significant increase of interfacial loss due to sluggish kinetics of oxygen reduction reaction at the cathode. In this study, I demonstrated both spectroscpic (AC impedance spectroscopy) and spectrometric (Nano secondary ion mass spectrometry) evidence that oxygen incorporation from the cathode into the electrolyte is significantly enhanced at grain boundaries of the electrolyte. The second part of work discusses a study focused on proton transport in proton- conducting ceramic fuel cells. Acceptor-doped perovskites have attracted recent at- tention as potential electrolyte materials for the next generation protonic devices, including fuel cells, because of their high ionic conductivity at intermediate temper- atures. The chemical instability of most of proton-conducting ceramics in acidic gas environments such as carbon dioxide, however, compromises their practical use. I discuss the evidence of proton conduction in nanoscale yttria-stabilized zirconia, well known oxide ion conductor; this points to its possible usage as a chemical barrier layer for proton-conducting ceramics. The third part of work presents a study of the possibility of extracting electricity from plant cell and the economic feasibility. Plants have developed sophisticated solar energy capture mechanisms that may be adapted to be less expensive or to perform better than current photovoltaic solar energy collectors. I discuss direct extraction of photosynthetic electrons from a single plant cell done by inserting nanoscale electrodes into their chloroplasts in vivo; these results may represent an initial step in generating high efficiency bioelectricity.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2011 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Park, Joong Sun |
|---|---|
| Associated with | Stanford University, Department of Mechanical Engineering |
| Primary advisor | Prinz, F. B |
| Thesis advisor | Prinz, F. B |
| Thesis advisor | Gür, Turgut M |
| Thesis advisor | Kenny, Thomas William |
| Advisor | Gür, Turgut M |
| Advisor | Kenny, Thomas William |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Joong Sun Park. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2011. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2011 by Joong Sun Park
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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