Book/Dissertation / PhD Thesis

FZJ-2026-02712

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Zinc-Based Catalysts for the Electrochemical CO2 Reduction

Stamatelos, I. (Corresponding author)FZJ*

2026
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-933-6

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Please use a persistent id in citations: urn:nbn:de:0001-2607011257043.435693342980  doi:10.34734/FZJ-2026-02712

Abstract: The electrochemical reduction of carbon dioxide, ECR, fueled by renewable energy sources, holds promise for addressing escalating greenhouse emissions and closing the carbon cycle. This thesis focuses on developing cost-effective catalysts to facilitate the electrochemical conversion of CO2 to CO. Utilizing low-temperature wet-chemical synthesis, zinc oxide, ZnO, based materials were synthesized and extensively characterized. The electrochemical characteristics and ECR performance of these materials were investigated in various electrolyzers, including H-cells, flow-cells, and zero-gap cells. Employing analytical techniques such as gas and ionic chromatography, we systematically mapped the product selectivity of different materials, offering detailed insights into the functions of the catalysts during ECR. To maximize the ZnO CO2-to-CO ECR capability, various ZnO allotropes were synthesized, revealing distinct differences in morphology and surface constitution. ZnO nanorods emerged as the most promising, exhibiting high ECR performance with a Faradaic Efficiency for CO FECO of over 80% in a current density range of 50–160 mA cm-2, in both flow-cell and membrane-electrode-assembly (MEA) electrolyzers. Despite an initial stability challenge attributed to the depletion of the ECR-active ZnO phase, an in-situ regeneration strategy was developed, demonstrating stable CO2-to-CO conversion for over 100 hours at 160 mA cm-2. To enhance direct and stable electrolysis, ZnO-based heterostructures decorated with d-block metal oxides of: Cu, Ni, Co, Fe, were explored. Among these, Cu/ZnO binary oxide showed the highest partial current density for CO jCO and exceptional stability of 30 hours with a FECO of 77% at 100 mA cm-2. The stabilizing effect of Cu on the ZnO phase enhanced overall ECR performance. Expanding our investigation, ternary Zn- Ce-Ag oxide catalysts were fabricated, achieving a FECO of 80% for 100 hours at 200 mA cm-2. Further addition of a small amount of silver, less than 10 wt. %, led to a structured core-shell morphology, resulting in a remarkable FECO of 90% at 200 mA cm-2, with exceptional stability for 200 hours in the MEA. This research offers critical insights into the design of efficient ECR catalysts, displaying their potential for real-world application in large-scale, of 100 cm2 active area, MEA electrolyzers. The catalysts developed not only advance fundamental understanding but also pave the way for the practical implementation of ECR technology.

Note: Dissertation, RWTH Aachen University, 2026

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Contributing Institute(s):

1. Elektrochemische Verfahrenstechnik (IET-4)

Research Program(s):

1. 1231 - Electrochemistry for Hydrogen (POF4-123) (POF4-123)

Appears in the scientific report 2026

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