Berner, Etienne (2024). Investigation of Dry Anodes Utilizing Electroplated Nickel and Nickel-Alloy Foam Catalysts for the Alkaline Oxygen Evolution in Anion Exchange Membrane Electrolyzers. (Thesis). Universität Bern, Bern
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Abstract
The dependence of modern society on fossil-based products is inherently connected to prosperity, well-being, wealth, and comfort. Conversely, the imperative to transition into a society powered solely by renewable resources and processes necessitates a fundamental change, not only in terms of technical advancements, but also in economic considerations and critical self-reflection. This study investigates the extensive domain of electricity-to-hydrogen conversion, which is considered to play a crucial role in the future fossil-free ammonia production. The conversion of ammonia into fertilizer is essential for ensuring global food security. The research approach to optimize the inherent reaction of oxygen evolution during electrochemical water splitting for hydrogen production is investigated by the mean of a gas diffusion electrode (GDE) setup in an alkaline environment. Recent advancements in water electrolysis have led to the development of anion exchange membrane water electrolyzers (AEMWE), which potentially combine the advantages of established alkaline electrolyzers with those of proton exchange membrane electrolyzers. The presented GDE setup is introduced as a “dry anode” configuration, subsequent to the recent introduction of the dry cathode in AEMWEs. This configuration can simulate reaction conditions of effective devices. Nickel and Ni alloy foams were synthesized using the hydrogen bubble template method, which generates highly porous metal films with enhanced surface area, thereby promoting an increased number of catalytically active sites and consequently higher reaction rates. Oxygen evolution rates, normalized to the geometric electrode area, reached substantial current densities at quasi steady-states exceeding 4 A cm-2 at an iR-corrected set potential of 2.1 V(RHE) for a pure Ni foam benchmark catalyst. Galvanostatic investigation of NiFe alloys demonstrated a current density of 3 A cm-2 for the optimal composition at 1.82 V(RHE), based on the statistical evaluation of an extensive dataset. In conclusion, the presented research demonstrates the potential of a dry anode configuration as an effective platform for studying high-performance oxygen evolution in an alkaline environment, supporting the development of advanced water electrolysis technologies.
| Item Type: | Thesis |
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| Dissertation Type: | Cumulative |
| Date of Defense: | 4 December 2024 |
| 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: | 17 Dec 2024 07:16 |
| Last Modified: | 17 Dec 2024 13:23 |
| URI: | https://boristheses.unibe.ch/id/eprint/5689 |
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