Electrochemical Carbon Capture via Engineered Polarized Liquid–Liquid Interfaces

Electrochemical carbon capture (ECC) is recognized as a promising route to mitigate carbon dioxide (CO2) emissions, especially as conventional amine-based processes face limitations due to high energy demands and chemical degradation. This study introduced an interface between two immiscible electrolyte solution (ITIES)-based electrochemical pH swing systems, enabling CO2 separation via facilitated ion transfer (FIT) of potassium cations, mediated by selective ligands such as quinidine. The ITIES configuration overcomes major barriers faced by ECC, namely, membrane challenges such as cost and fouling, oxygen sensitivity, and aqueous-phase solubility constraints, by leveraging organic-phase ligands. Experimental investigations included cyclic voltammetry, chronoamperometry, and continuous pH monitoring to analyze operational potential windows (0.27–0.58 V), quinidine speciation, and interfacial transfer mechanisms. Carbon capture experiments using bicarbonate-rich electrolytes demonstrated significant CO2 desorption and pH modulation, with measured energy consumption ranging from 110 kJ/mol to 314 kJ/mol CO2. Thermodynamic modeling and parametric analysis identified the bicarbonate concentration as the dominant driver of energy efficiency, with optimal conditions at 0.50 M, reducing specific energy consumption to 62 kJ/mol CO2. The system achieved significant CO2 capture at modest applied potentials (0.4–0.5 V). The gap between the theoretical model and experimental results showed that kinetic losses and parasitic side reactions are the main system limitations. The findings establish ITIES-driven ECC as a robust, tunable, and membrane-free alternative for the next-generation carbon capture, with direct implications for point-source industrial emission mitigation.