BORIS Theses

BORIS Theses
Bern Open Repository and Information System

Stability of Zero-gap CO2 Electrolyzers for Electrochemical CO Production

Liu, Menglong (2024). Stability of Zero-gap CO2 Electrolyzers for Electrochemical CO Production. (Thesis). Universität Bern, Bern

24liu_m.pdf - Thesis
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The unchecked massive emissions of the greenhouse gas CO₂ through the continued use of fossil fuels is the main cause of global warming of the earth's atmosphere with dramatic consequences for our environment. Reducing global CO₂ emissions and controlling CO₂ concentrations in the atmosphere are currently among the greatest global challenges facing our society. The electrochemical CO₂ reduction reaction (referred to as ec-CO₂RR), capable of converting polluting CO₂ back into valuable chemicals such as carbon monoxide (CO) and formate using excess renewable energy, offers a promising approach to mitigate this problem. Socio-economic assessments have shown that carbon monoxide is a high-value ec-CO₂RR product and a platform chemical in the chemical industry. This is why this PhD project focused on the optimization of CO₂-to-CO conversion by electrochemical means. To achieve industrially relevant current densities in the order of several hundred milliamperes per square centimeter, the use of so-called gas diffusion electrodes (GDEs) is essential. One of the biggest problems currently preventing the use of this technology on a large scale is the stability of these GDEs. In this PhD project, the stability of GDEs is therefore systematically investigated using nanoparticulate silver catalysts in combination with a so-called semi-zero-gap test cell configuration (Arenz design). Using novel analytical approaches that can detect and quantify the transport of electrolyte through GDEs during CO₂ electrolysis (referred to as perspiration), various experimental factors (e.g., the use of binder materials, harmful use of capping agents, defectivity of GDEs, chemical nature of alkali metal cations, etc.) that stabilize or destabilize the GDEs could be identified. Active water/electrolyte management has been shown to be essential for prolonged operation of this kind of electrolyzers. Furthermore, a novel concept for stabilizing the nanoparticulate silver catalysts was developed. This is based on embedding the nanoparticles in a matrix of anion-conductive binder materials, which largely suppresses cathodic corrosion of the catalyst material during extended electrolysis. The results of this PhD thesis pave the way for a rational design of GDEs for future industrial applications of electrochemical CO₂ conversion.

Item Type: Thesis
Dissertation Type: Cumulative
Date of Defense: 15 January 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: 25 Jan 2024 11:27
Last Modified: 25 Jan 2024 11:32

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