| Abstract Scope |
This work presents low-temperature, electrochemically driven systems utilizing hydroxides to bypass energy-intensive thermal regeneration in CO₂ capture. Alkali and alkaline earth hydroxides are cheap, abundant, and highly reactive towards CO₂, making them ideal, cost-effective CO₂ absorbents. First, we establish a Ca-based loop and uses an electrochemical pH gradient to dissolve CaCO₃ and precipitate Ca(OH)₂. In ambient air capture, adding NaOH to the Ca(OH)₂ slurry optimizes gas absorption at 55 ºC. Second, to eliminate slurry transport, a precipitate-free electrochemical system using aqueous sodium sulfate electrolyte captures CO₂ in the catholyte from air or flue gas and releases it upon mixing with the acidic anolyte. Finally, we adapt this chemistry to mobile emissions, demonstrating an onboard CO₂ capture strategy for internal combustion engine exhaust using hydroxide absorbents. Besides co-producing green H₂, these adaptable electrochemical loops eliminate high-temperature calcination, offering scalable stationary and mobile carbon-negative pathways. |