Electrochemically-Driven Solution-Phase CO₂ Capture

We investigate the mechanisms of and demonstrate the efficacy of CO₂ capture/release systems based on several thermodynamic cycles undertaken by aqueous solutions. Low-energy electrochemically-driven methods of making acid and base enable CO₂ capture by reaction with hydroxide and release upon acidification. Reactions among the various species of dissolved inorganic carbon (DIC) leading to CO₂ absorption and outgassing are caused by, respectively, diluting and concentrating the alkalinity in a solution. Redox-active organic molecules can reversibly bind CO₂ directly in one redox state and release it in the other. The same molecules can swing the pH by undergoing proton-coupled electron transfer, thereby enabling CO₂ capture by hydroxide.