Efficient and stable electrochemical carbon capture via integrated CO2 absorption and regeneration

Abstract

Carbon capture in electrochemical cells generally relies on the local pH difference at the two electrodes, which results in high pH overpotentials and high energy consumption. Here, we integrate CO₂ absorption and in situ CO₂/sorbent regeneration steps in a single electrochemical reactor for reduced energy consumption, a simplified process design, and improved reactor stability. By directly feeding the carbon source into the cathode chamber while performing the CO₂ and sorbent regeneration electrolysis from (bi)carbonate solutions, we successfully demonstrate in-cell carbon capture and the mitigation of local pH elevation, which effectively reduces the pH overpotentials and enhances the electron efficiency. Our system enables predominant bicarbonate-based CO₂ capture under point-source conditions, requiring only ∼48 kJ mol⁻¹ CO₂ for onset capture and ∼180 kJ mol⁻¹ CO₂ at 100 mA cm⁻². This strategy achieves 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 1000 hours, with the cation transport efficiency maintained above 80%.