Dodwell, James Alexander;
(2022)
Electrocatalyst Degradation in Polymer Electrolyte Membrane Water Electrolysers.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Polymer electrolyte membrane water electrolysis (PEMWE) is predicted to become one of the backbone technologies of the future ‘hydrogen economy’, but for this to be realized several obstacles must be overcome. Importantly, an understanding of PEMWE system lifetime is incomplete as the various degradation routes have not been fully characterized or quantified. In this thesis several improvements to this understanding are presented. Firstly, time-based in situ open circuit voltage (OCV) data under a range of relevant ambient pressure conditions are presented. The impact of aqueous and gaseous environments has been elucidated, and it has been shown that potential change during OCV may proceed on either the anode, cathode or neither. These practical results have been enhanced with a basic model of OCV which shows that there is no universal OCV profile that can be applied to all PEMWE conditions. The impact of cathode potential change during OCV on the degradation of platinum has also been established. By the coupling of a 3-electrode PEM electrolyser cell, and using a differential pulse voltammetry technique, Pt dissolution from the cell was detected when the cathode potential rose above 0.85 V versus the normal hydrogen electrode (NHE). This reached a maximum dissolution rate at the highest cathode potential of 1.02 V NHE, and gradually decayed over an approximately 100 h period. This was established during OCV both on Pt black (PtB) and Pt on carbon (Pt/C) electrocatalysts. It was demonstrated that, in the case of Pt/C, the dissolution phenomenon may impact the lifetime of the PEMWE system to less than 5 years. It has been clearly shown that OCV conditions cause degradation of the cathode electrocatalyst, and so must be considered when evaluating PEMWE lifetime.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Electrocatalyst Degradation in Polymer Electrolyte Membrane Water Electrolysers |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2022. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10158014 |
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