Electrode surface activation and nanostructuring effects on fuel cell performance
Abstract/Contents
- Abstract
- Fuel cells are an attractive clean energy technology due to the low or zero emissions from operation and the potentially high efficiency. However, several challenges exist that hinder the implementation of fuel cells as a part of portable power devices. Among these challenges are the losses inherent to fuel cell operation. This work presents the results of three studies that attempt to lower activation losses on the fuel cell anode by catalysis or increased reaction area. The first study focuses on the anode electrochemistry for a novel fuel cell device that utilizes the naturally occurring charge separation in photosynthesis as the electrolyte. The second study investigates the use of an oxide ion conducting electrolyte and a PtRu anode for a direct methanol fuel cell at temperatures much lower than previously considered feasible. The third study examines the fabrication of high-surface area mixed electronic and ionic conducting anodes and their impact on fuel cell performance. The latter two studies are motivated by interest in low-temperature direct methanol fuel cells for mobile devices, while the former was an exploratory investigation into the possibility of "bioelectricity", which may more appropriately have been called a "photosynthetic fuel cell". Photosynthesis energizes electrons obtained through hydrolysis in the thylakoid space and through a series of steps, reduces the charge-carrying protein ferredoxin (Fd). The charge on Fd is used in numerous processes throughout the cell. It is well established that Fd does not readily give up its charge to a bare metal electrode. Therefore, mediators or surface modifiers must be used to capture this high-energy electron. The bioelectricity investigation studied the effects of various chemical modifiers attached to gold electrodes on the electrooxidation of reduced Fd and found that poly-L-lysine covalently bound to a monolayer of mercaptoundecanoic acid on gold resulted in reasonable oxidation kinetics. Typical solid oxide fuel cells operate at temperatures above 600°C. It was found in the second study that a PtRu anode was effective in low temperature (250-450°C) direct methanol operation using yttria-stabilized zirconia (YSZ), (Y2O3)0.08(ZrO2)0.92, as the electrolyte. In this arrangement, methanol may be used without equimolar quantities of water, in contrast to typical direct methanol fuel cells (DMFCs). Electrochemical impedance spectroscopy (EIS) measurements were analyzed in an effort to better understand the rate-limiting processes. In the third study presented in this work, the fabrication of high-surface are mixed electronic and ionic conducting (MEIC) anodes is discussed, along with the results of fuel cell characterization with MEIC anodes of high surface area. In particular, fuel cells fabricated using yttrium-doped BaZrO3 (BYZ) electrolytes are studied with high surface area Pd anodes for use with H2 and methanol fuels.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Copyright date | 2011 |
| Publication date | 2010, c2011; 2010 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Komadina, Jason David |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering |
| Primary advisor | Prinz, F. B |
| Thesis advisor | Prinz, F. B |
| Thesis advisor | Cui, Yi, 1976- |
| Thesis advisor | McIntyre, Paul Cameron |
| Advisor | Cui, Yi, 1976- |
| Advisor | McIntyre, Paul Cameron |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Jason David Komadina. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2011. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2011 by Jason David Komadina
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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