Efficient and Stable Electrochemical Carbon Capture via Integrated CO2 Absorption and Regeneration

Abstract

Carbon capture in electrochemical cells generally relies on the local pH differences at the two electrodes, which results in high pH overpotentials and high energy consumption. Here, we integrated CO2 absorption and in-situ CO2/sorbent regeneration steps in a single electrochemical reactor for reduced energy consumption, simplified process design, and improved reactor stability. By directly feeding carbon source into the cathode chamber while performing CO2 and sorbent regeneration electrolysis from (bi)carbonate solutions, we successfully demonstrated an in-cell carbon capture and mitigation of local pH elevation, which effectively reduces the pH overpotential and enhances the electron efficiency. Our system captures CO2 predominantly in the form of bicarbonate, requiring only ~48 kJ mol-1 CO2 for onset capture and ~180 kJ per mol CO2 at 100 mA cm-2. This strategy delivers high sorbent utilization efficiency, improved electron utilization, and reduced energy consumption, enabling stable carbon capture operation (3.5% CO2 concentration input) at 50 mA cm-2 for over 1,000 hours, with a cation transport efficiency maintained above 80%.