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Engineering Nanoelectrocatalytic Systems for CO2 and Nitrate Conversion into Value-Added Chemicals
The thesis addresses two major related environmental crises: nitrate pollution of water systems and the ever-increasing levels of atmospheric carbon dioxide. Both challenges are closely linked to anthropogenic disturbance of nitrogen and carbon cycles and require sustainable, energy efficient mitiga...
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| Format: | Thesis |
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AUC Knowledge Fountain
2026
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| Summary: | The thesis addresses two major related environmental crises: nitrate pollution of water systems and the ever-increasing levels of atmospheric carbon dioxide. Both challenges are closely linked to anthropogenic disturbance of nitrogen and carbon cycles and require sustainable, energy efficient mitigation techniques. In this study, we investigate electrochemical conversion routes as a unified approach to convert these pollutants into value-added compounds: ammonia (NH3) via nitrate reduction (NO3-RR) and ethylene (C2H4) via carbon dioxide reduction (CO2RR). The first half of this work deals with the design and engineering of Cu-Zn alloy electrocatalysts for efficient NO3-RR. Tuning the alloy composition and surface nanostructure improved the catalytic activity, selectivity, and stability for ammonia generation. The improved activity is ascribed to the synergistic effect of Cu and Zn, which modulate the adsorption energies of crucial reaction intermediates, promote hydrogenation pathways, and inhibit the competing hydrogen evolution reaction. Atomistic insights into the reaction mechanism were obtained from density functional theory (DFT) calculations, which revealed modulation of the electronic structure and the adsorption energetics of nitrogen-containing intermediates, explaining the experimentally observed enhancement in catalytic performance. The second half focuses on nanostructured copper-based catalysts, namely copper nanofiber architectures, for selective CO2 electroreduction to multi-carbon (C2+) products. The nanofiber shape provides a large surface area and numerous active sites, facilitating improved CO adsorption and promoting C-C coupling, a crucial step toward ethylene production. Furthermore, the DFT analysis reveals the chemical pathways and identifies the critical intermediates that drive the C–C bond formation, thereby providing a mechanistic insight into the enhanced selectivity for ethylene. This work further integrates basic electrochemical concepts, catalyst design techniques, and system-level considerations (e.g., electrolyzer topologies and reaction conditions) to provide a comprehensive understanding of NO3-RR and CO2RR processes. Combining experimental electrochemical analysis and theoretical modeling, the structure-activity-selectivity correlations in both systems are established. In summary, this thesis demonstrates the rational design of catalysts, guided by theoretical insights from DFT simulations, to efficiently convert nitrogen and carbon pollution into useful chemical products. These findings, in combination, call for the development of sustainable circular techniques in both environmental remediation and energy conversion, furthering the practical deployment of electrochemical technology. |
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