Degree
Doctor of Philosophy (PhD)
Department
Chemical Engineering
Document Type
Dissertation
Abstract
The electrochemical reduction of CO₂ offers a promising route to sustainable chemical production, converting atmospheric carbon into valuable feedstocks using renewable electricity. This dissertation elucidates the mechanisms governing selective CO₂ electroreduction to C₁ and C₂ products, achieving Faradaic efficiencies up to 90%, and advances the technology toward industrial viability through electrocatalyst design, mechanistic understanding, electrolyte optimization, and reactor engineering. Copper-based alloy electrocatalysts achieved record selectivity for C₂ products, ethylene (73% FE), ethanol (60% FE), and acetate (50% FE), at current densities above 400 mA cm⁻² with stable operation up to 400 hours. In situ X-ray absorption, XPS, XANES/EXAFS, XRD, SEM-EDS, and Auger spectroscopy confirmed Cu⁺ persists kinetically despite thermodynamic instability, underlying a common acetyl intermediate governed by partial positive charge on neighboring copper atoms (Cuᵟ⁺). DFT calculations correlated Cuᵟ⁺ with selectivity and active-site density, where low favors ethylene, moderate favors ethanol, and high favors acetate.
Electrolyte engineering showed selectivity is governed by CO surface coverage rather than pH alone; weakly acidic conditions limit CO₂ activation and favor ethylene, while higher pH raises CO coverage and redirects selectivity toward ethanol and acetate via hydrogenation, confirmed by CO/CO₂ co-feed experiments. Marcus theory analysis showed the dominant proton donor for hydrogen evolution shifts from water at pH 14 to phosphate species at pH 6, enabling ethylene formation without excessive HER. Conventional membrane electrode assemblies suffered severe product crossover, up to 96% loss, rendering recovery economically infeasible. A proprietary flowing-electrolyte interlayer and dual-membrane electrolyzer resolved this, reducing crossover to below 2% and enabling direct route from CO₂ to organic carbonates.
A concluding techno-economic and life-cycle assessment benchmarked these products against fossil, bio-based, and CCS-augmented incumbents. C₁ products approached fossil cost parity, with CO at $0.32, formic acid $0.40, and methanol $0.68 kg⁻¹, while C₂ products cost roughly twice as much, with ethylene at $2.05 and ethanol $1.36 kg⁻¹, except acetic acid, which reached parity at $0.90 kg⁻¹ while achieving the lowest carbon footprint at 0.2 kg CO₂eq kg⁻¹ and Pareto dominance over its incumbent. Electrolyzer-derived products enabled Spirulina cultivation, cellulose acetate synthesis, and carbonate ester production, advancing electrochemical CO₂ conversion toward sustainable chemical production.
Date
9-23-2026
Recommended Citation
Dauda, Monsuru Olatunji, "SUSTAINABLE CHEMICAL PRODUCTION THROUGH ELECTROCHEMICAL CONVERSION OF CO2" (2026). LSU Doctoral Dissertations. 7202.
https://repository.lsu.edu/gradschool_dissertations/7202
Committee Chair
Dr. John C. Flake
LSU Acknowledgement
1
LSU Accessibility Acknowledgment
1