Advancing CO₂ Capture and Electrochemical Conversion in Nonaqueous Electrolytes

Mitigating carbon dioxide (CO₂) emissions is a defining challenge of our time, demanding transformative solutions for sustainable energy and chemical manufacturing. Electrochemical CO₂ reduction (CO₂R) offers a promising pathway to convert waste carbon into valuable products, but its deployment at scale is hindered by the parasitic hydrogen evolution reaction (HER) and poor compatibility with industrial capture streams. This dissertation advances a new framework for integrating CO₂ capture and electrochemical conversion using nonaqueous electrolytes. By treating the electrolyte not as an inert medium but as an active design space, this work identifies molecular-level strategies to control CO₂ speciation, reactivity, and transport. In Chapter 2, we study the role of alkali cations in aprotic systems and identify carbonate precipitation as the primary cause of electrode deactivation. By introducing dilute acid additives, we mitigate carbonate formation and enable sustained CO₂ reduction. In Chapter 3, we probe the influence of electrolyte anions and solvation structures, demonstrating that weakly coordinating solvents such as dimethyl sulfoxide (DMSO) minimize ion aggregation and promote higher CO₂ reduction activity and selectivity. Chapter 4 explores the effect of water in nonaqueous electrolytes, showing that solvent-water hydrogen bonding can be tuned to suppress hydrogen evolution while maintaining high selectivity. Finally, in Chapter 5, we leverage these insights to develop an integrated CO₂ capture and conversion strategy using monoethanolamine (MEA) in DMSO. We show that nonaqueous electrolytes favor the formation of neutral carbamic acid adducts, enhancing CO₂ uptake and enabling CO formation with Faradaic efficiencies exceeding 80%. Importantly, we demonstrate that earth-abundant zinc catalysts can replace precious metals without sacrificing performance, leading to significant cost reductions. A techno-economic analysis highlights the commercial viability of this approach compared to aqueous systems. This work establishes molecular-level design rules for nonaqueous electrolytes and provides a framework for future development of integrated CO₂ capture and conversion technologies for sustainable chemical manufacturing.