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Mar, Harrison

University of British Columbia

The urgent need to address global climate challenges has heightened the importance of reducing CO₂ emissions and developing sustainable carbon utilization methods. CO₂ electrolysis (CO2E) is an emerging carbon utilization method that can convert captured CO₂ into various products while closing the carbon loop in pursuit of achieving global climate targets. The development of improved materials and electrolyser designs has enabled CO2E to reach commercially relevant current densities, voltages, and faradaic efficiencies, however, achieving all of these in unison along with high stability remains a challenge. Barriers to furthering progress include the high kinetic losses associated with CO₂ reduction, H₂ evolution at the cathode, and slow mass transportation of CO₂ reactant, all of which can be improved by optimizing electrode and cell design. A reference electrode is a tool that can help the development of electrodes, materials, and cell design by decoupling electrode processes from one another during operation. Decoupling various overpotentials using reference electrodes within electrolysers and fuel cells has been well documented, but their application in CO2E cells is limited, and remains challenging to incorporate reference electrodes into electrochemical cells while ensuring accurate measurements and minimal obstruction of cell performance. In this thesis, a method for bipolar membrane deposition was developed to improve CO2E to multicarbon faradaic efficiency while reducing cell voltage and H₂ evolution. Then, an electrolyser cell which incorporates an edge-type reference electrode was developed to decouple anode and cathode potentials throughout CO2E stability tests for up to 300 hours. Results show that the cell is capable of separating potential measurements for extended testing and is recommended for future stability studies, and that electrode alignment and understanding electrode kinetics are critical to obtain accurate electrochemical impedance spectroscopy for 3-electrode measurements. Finally, this cell design was extended to anion-exchange membrane water electrolysis (AEM-WE) to test its wider applicability, which showed the ability to decouple anode and cathode degradation through 3-electrode cyclic voltammograms. These findings contribute a method of improving membrane performance in CO₂ electrolysers, and present a cell design that can be used as a tool to monitor in-situ degradation of MEA components under extended operation.

Text

2025-04-24

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89096

Forestry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/