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Abstract: The industrial era has brought a never-ending problem to civilization through the emission of greenhouse gases (GHGs) while extracting energy from fossil fuels for a variety of processes. Among different GHGs, carbon dioxide (CO2) stood out as one of the most impactful and dangerous gases causing climatic disasters around the globe. However, CO2 as the abundant C1 building block, through the conversion pathways gives a plethora of opportunities to convert it into a wide range of commercial products and applications. The holistic approach among different conversion pathways is the electrochemical reduction of CO2 (eCO2R), ideally powered by renewable energy from intermittent sources such as wind and solar power. A silver bullet of the process is to find a catalyst that is active, selective, and stable. Copper has been recognized as the only monometallic catalyst that can produce products that require a transfer of >2e-. However, in recent years the increased awareness of its reconstructive nature under eCO2RR-relevant conditions multiplied the complexity of the parameters that can influence the reaction. Therefore overall thesis's approach to studying copper-based catalysts is based to understand the reconstructive aspect and the stability of Cu-based catalysts, and deeply comprehend their relationship with the activity/selectivity. Chapter 1 gives an introduction to the recent activities in the field of carbon capture, utilization and storage (CCSU) technologies, the fundaments of CO2 as a molecule, and its pathway toward state-of-the-art discoveries in the eCO2 R reaction. Afterward, the thesis focuses on the main experimental technique to produce nanostructured copper-based materials, namely, electrodeposition (Chapter 2). A big part of the thesis focuses on the establishment of an electrochemical setup for activity/selectivity measu rement. The setup consists of two parts: 1) construction of the custom-made gas-tight sandwich-type electrochemical cell and 2) optimization of the online gas and ex-situ liquid product detection. After the establishment of the reliable electrochemical setup, Chapter 3 focuses on electrochemically -grown Cu2O nanocubes catalyst and how the reconstructive nature induced by a particular electrochemical protocol influences on boost in activity/selectivity for methane production. The last part of the thesis consists contribution to the fundamental understanding of the degradation mechanisms and stability of Cu -based catalysts under eCO2RR conditions. A unique ex-situ approach, mirrored in identical location scanning electron microscopy (IL-SEM) method is employed to study electrodeposited spherical half-micron particles on the glassy carbon rotating disk electrode (GC-RDE). With this evidence, we could interpret the observed structural changes as two separate electrochemical processes occurring one after another, namely copper dissolution from pre-oxidized native nanoparticles and subsequent (electro -) redeposition of the dissolved copper species in a form of n ew smaller Cu fragments.
Keywords: electrocatalysts, electrochemical CO2 reduction, copper nanoparticles, IL-SEM, stability, degradation
Published in RUNG: 14.11.2023; Views: 760; Downloads: 12
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