Electrochemical Reduction of CO2 to Acetate: The role of copper-based catalysts

This experimental thesis was carried out in the United States at the University of California, Irvine (UCI), under the supervision of Prof. Stefania Specchia and Prof. Plamen Atanassov, together with his research group. The work focused on the synthesis, characterization, and evaluation of the electrocatalytic activity of different copper-based catalysts for the electrochemical reduction of carbon dioxide (CO₂RR). In particular, three new catalysts were synthesized — two copper-based and one containing silver nanoparticles — using a synthesis method previously employed by the group for platinum- and cobalt-based catalysts, adapted here to the chemical compounds of interest. After synthesis, the research shifted to their characterization, using X-ray diffraction (XRD) and transmission electron microscopy (TEM) to verify the crystalline phases, as well as the morphology and particle size of the obtained catalysts. Finally, the catalytic performance toward CO₂ electroreduction was tested using flow cells, electrolyzers equipped with a gas diffusion electrode (GDE), which help to overcome mass transport limitations of the gaseous reactant. In parallel, the effect of pH on the distribution of liquid products from CO electroreduction was also investigated, using commercial copper nanoparticles as the catalyst in the same flow cell setup. The products obtained from these experiments were quantified using high-performance liquid chromatography (HPLC), which allowed us to analyze trends as a function of both pH and applied cell voltage. The thesis is organized into the following chapters: •??Chapter 1: General introduction on sustainability and the current state of CO₂RR, with a focus on its theoretical foundations and the different systems used. •??Chapter 2: Description of the materials employed, the synthesis and characterization methodologies for the new catalysts, and the instrumentation used for product quantification. A summary of the main experimental tests is also provided. •??Chapter 3: Presentation and discussion of the obtained results, supported by figures and graphs. •??Chapter 4: Conclusions and future perspectives.