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Title: Applications of In Situ Spectroscopy Towards the Mechanistic Elucidation of Electrocatalytic Carbon Dioxide Reduction
Authors: Pander, James
Advisors: Bocarsly, Andrew B.
Contributors: Chemistry Department
Keywords: Carbon Dioxide Reduction
Infrared Spectroscopy
In Situ Spectroelectrochemistry
Post Transition Metal
Subjects: Chemistry
Issue Date: 2016
Publisher: Princeton, NJ : Princeton University
Abstract: The electrochemical reduction of carbon dioxide to value-added products is an attractive method for simultaneously providing renewable carbon-based fuel sources in order to maintain the use of the current energy infrastructure and mitigate the environmental impact of burning fossil fuels. In order for this approach to be energetically viable, an appropriate electrocatalyst is necessary to facilitate the transformation of carbon dioxide to the desired product. The mechanisms through which many electrocatalysts facilitate these transformations have oftentimes been under-studied. One method to gain useful mechanistic information about these chemical reactions involves spectroelectrochemistry, the simultaneous application of electrochemical and spectroscopic techniques. This work demonstrates the application of various in situ spectroelectrochemical techniques towards elucidating the mechanism of carbon dioxide reduction on both molecular and heterogeneous catalytic materials. UV-vis spectroelectrochemistry is used to determine the oxidation state of a molecular cobalt porphyrin catalyst during the reduction of carbon dioxide to carbon monoxide, observing an initial one electron reduction from CoII to CoI. Additionally, ATR-IR spectroelectrochemistry was utilized to probe the role of surface oxide species in the reduction of CO2 to formate at posttransition metal electrodes (In, Sn, Pb, Bi) and their alloys. Despite the fact that these electrodes produce the same product, it was shown that their facilitation of the chemical reaction proceeds through three different mechanisms. Specifically, indium and tin are oxide-active, meaning a metastable oxide interacts with carbon dioxide to form a surfaceiv bound carbonate intermediate. Lead was found to be oxide-buffered, meaning that a metastable oxide plays a critical role in the reduction mechanism; however, carbon dioxide reduction occurs at metallic sites instead of oxide sites. Finally, bismuth was found to be oxide-inactive, meaning that a dynamic metastable oxide is not observed and does not play a direct role in the reduction mechanism. Indium-tin alloys were determined to reduce carbon dioxide through the same mechanism as the parent materials, but with higher efficiency and lower overpotential.
Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog:
Type of Material: Academic dissertations (Ph.D.)
Language: en
Appears in Collections:Chemistry

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