Electrochemical reduction of carbon dioxide on transition metal surfaces [electronic resource]
- Kendra Kuhl.
- Physical description
- 1 online resource.
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|3781 2013 K||In-library use|
- Kuhl, Kendra.
- Jaramillo, Thomas Francisco, primary advisor.
- Chidsey, Christopher E. D. (Christopher Elisha Dunn), advisor.
- Hodgson, Keith, advisor.
- Stanford University. Department of Chemistry.
- Electrochemical carbon dioxide reduction reaction (CO2RR) is a promising way to store energy from intermittent electricity sources (ie. wind and solar) and for the synthesis of carbon-based compounds that are currently derived from fossil fuels. To commercialize this process, catalysts that selectively reduce CO2 at low overpotential are needed. Research in this area is hindered by the experimental difficulty of comparing catalyst activity. This thesis begins with the development of a custom electrolysis cell that can be coupled to product detection with NMR and GC. This method allows for accurate voltage measurement and the quantification of all possible products to give the most complete characterization of CO2RR activity available to date. The CO2RR activity of Cu metal is well-studied, but application of this more sensitive experimental method lead to the identification of five novel products: glyoxal, glycolaldehyde, ethylene glycol, hydroxyacetone, and acetone. The CO2RR product identities and their potential dependence inspired the hypothesis that the enol and diol forms of the products may be the active intermediate species on the electrode surface. CO is believed to be an intermediate of CO2RR to methane and ethylene and the direct electrochemical reduction of CO confirmed that it is also a possible intermediate in the formation of many of the novel products observed as well. After Cu, the activity of Au, Ag, Zn, Ni, Pt, and Fe for CO2RR was also measured using the same experimental method. This represents the most complete dataset of transition metal activity available and reveals several important trends. A plot of CO2RR activity vs. CO binding energy places Au at the top of the volcano, suggesting that it has a near optimal binding energy for CO (and other intermediates) within the pure metals. A strong CO binding energy is also correlated with an early onset potential for HER and methane/methanol formation. The widespread use of CO2RR will require a catalyst with higher activity than any of the pure metals. Efforts to improve activity began by alloying Fe and Ni, which are poor overall CO2RR catalysts individually, but do produce hydrocarbon products. Alloying decreased the overpotential of needed for methane formation, demonstrating that alloying is a promising method of catalyst improvement.
- Publication date
- Submitted to the Department of Chemistry.
- Thesis (Ph.D.)--Stanford University, 2013.
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