Schlegel, Nicolas (2023). Investigations into the Product-oriented Glucose Electrooxidation: From Gold Towards High-entropy Alloy Catalysts. (Thesis). Universität Bern, Bern
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Abstract
The glucose oxidation reaction (GOR) has gathered increased interest from various fields in the last decades. Besides the more prominent bioelectrocatalytic applications, glucose sensors and direct glucose fuel cells, the product-oriented GOR has more recently gained increased attention, due to the promising application of the oxidation products as smart drop-in chemicals. This thesis is concerned with the electrochemical oxidation of glucose and the identification of operational parameters that promote the efficient formation of glucaric acid. Working in a classical three-electrode RDE setup the influence of forced convection on the product distribution was investigated. The reaction pathway from glucose to glucaric acid was explored by oxidizing glucose as GOR reaction intermediates. To understand the reaction pathway, a high-performance liquid chromatography (HPIC) method was developed which can quantify intermediates and undesired side-products. Combining experimental data using a gold disk electrode and insights gathered from DFT calculations, the selective oxidation of terminal hydroxyl groups has been identified as the most challenging step for forming glucaric acid selectively and efficiently. Additionally, the oxidation of the aldehyde group in glucose is shown to occur fast and selectively. Overcoming the limitation of the Au-electrode, high-entropy alloys (HEA) have been envisaged as potential catalysts for the GOR. A synthesis approach based on incipient wetness impregnation (IWI) yielding supported single-phase HEA nanoparticles was developed. This facile and reliable method allows for nanoparticle size-control by varying different synthesis parameters. A model system of PtFeCoNiPd was investigated in detail by combining in-situ X-ray diffraction (PXRD) and in-situ X-ray absorption (XANES). The combination of both analysis techniques enables linking phase transformations and changes in the unit cells to the reduction behavior of the individual constituent elements.
| Item Type: | Thesis |
|---|---|
| Dissertation Type: | Cumulative |
| Date of Defense: | 3 July 2023 |
| Subjects: | 500 Science > 540 Chemistry 500 Science > 570 Life sciences; biology |
| Institute / Center: | 08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP) |
| Depositing User: | Hammer Igor |
| Date Deposited: | 13 Aug 2024 12:34 |
| Last Modified: | 22 Aug 2024 03:03 |
| URI: | https://boristheses.unibe.ch/id/eprint/5358 |
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