Electrocatalysis by surface immobilized discrete molecular complexes
Abstract/Contents
- Abstract
- Direct methanol fuel cells are a promising means of generating electricity from methanol and dioxygen. However, state of the art catalysts for the oxidation of methanol and reduction of dioxygen must operate at significant overpotentials to obtain reasonable reaction rates. Finding alternative catalysts operative at lesser overpotentials would make direct methanol fuel cells more attractive. Among the many alternative catalyst designs that have been explored, the use of discrete molecular complexes is particularly appealing as molecular structure may be methodically modified to provide mechanistic insight. Such surface immobilized metal complexes have shown activity towards alcohol and water oxidation as well as dioxygen reduction. Described herein, are advances made in the development of discrete molecular complexes for methanol oxidation and dioxygen reduction. A ruthenium polypyridyl complex covalently attached to a carbon electrode shows methanol oxidation. Benzyl alcohol oxidation is used as a benchmark to compare with related complexes. This complex shows a 240 mV decrease in overpotential for benzyl alcohol oxidation compared to the best surface immobilized ruthenium polypyridyl complexes, an order of magnitude larger turnover frequency, and a 15% improvement in faradaic efficiency. Pourbaix and mechanistic analysis suggests that the active oxidant is a RuIV=O complex. Formation of this active catalyst is strongly dependent on surface immobilization under dry, inert atmosphere conditions. Methanol oxidation is not observed from carbon electrodes under aqueous surface immobilization conditions. Nor is methanol oxidation observed from metal oxide electrodes under nonaqueous immobilization treatment. Thus, the surface, the tether bonding the discrete molecule to the surface, and the solution, contribute to forming this active electrocatalyst. The organized distribution of binuclear copper complexes on a carbon electrode significantly enhances dioxygen reduction compared to a random distribution of mononuclear copper complexes. Nafion coatings enhance the stability of the surface immobilized molecular complex. Surface immobilized discrete metal complexes are significantly more robust than complexes prepared from metalation of surface immobilized ligands. These results highlight the value of surface immobilized discrete metal complexes as electrocatalysts.
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 | Cook, Thomas Carlson | |
|---|---|---|
| Degree supervisor | Stack, T. (T. Daniel P.), 1959- | |
| Thesis advisor | Stack, T. (T. Daniel P.), 1959- | |
| Thesis advisor | Chidsey, Christopher E. D. (Christopher Elisha Dunn) | |
| Thesis advisor | Xia, Yan, 1980- | |
| Degree committee member | Chidsey, Christopher E. D. (Christopher Elisha Dunn) | |
| Degree committee member | Xia, Yan, 1980- | |
| Associated with | Stanford University, Department of Chemistry. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Thomas Carlson Cook. |
|---|---|
| Note | Submitted to the Department of Chemistry. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Thomas Carlson Cook
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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