Sulfonated anthraquinone for enhanced electrochemical CO2 capture via improved solubility and redox kinetics

Electrochemically mediated carbon capture (EMCC) based on redox-active CO 2 carries is regarded as a promising pathway for carbon capture under mild conditions. Owing to their reversible electron-transfer capability, quinones have been widely researched in aqueous EMCC systems. However, their highly symmetric structure severely restricts solubility, which adversely affects the electrochemical efficiency and stability in non-aqueous systems. Here, we introduce sulfonate groups (–SO 3 − ) into the anthraquinone molecule to modulate the molecular polarity and suppress π-π stacking, significantly improving solubility and optimizing capture performance. Research revealed that 2-AQS exhibits optimal solubility, viscosity, conductivity, and electrochemical properties. During the 120 h of electrochemical CO 2 capture, it maintained a capacity retention rate of 76.35% and a coulombic efficiency of 85.06%, with an energy consumption of 285.92 kJ·mol −1 , markedly lower than that of unmodified AQ (498.23 kJ·mol −1 ). This work reveals the impact of sulfonate functionalization on the EMCC performance of anthraquinone derivatives, providing a balanced and cost-competitive candidate (2-AQS) for practical EMCC applications.