Reversible Carbon Dioxide Capture and Release using an Electropolymerized Anthraquinone Electrode in Aqueous Solution

The rise of carbon dioxide (CO₂) in the atmosphere is closely linked to global climate change, driving the need for efficient carbon capture technologies. This study investigates the electrochemical carbon capture capabilities of the polymer poly-1-aminoanthraquinone (p-1-AAQ) when coated onto glassy carbon and carbon paper electrodes. This polymer is synthesized from cheap materials using facile, oxidative electropolymerization and provides high cyclic stability. Cyclic voltammetry and potentiostatic "electroswing" methods were employed together with infrared spectroscopy detection to study CO₂ capture and evaluate Faradaic efficiency under acidic, neutral, and alkaline conditions. These results indicate that coated glassy carbon electrodes offer significantly higher Faradaic efficiencies than carbon paper (CP). However, carbon paper electrodes still displayed an exemplary maximum capture efficiency of 76%, showing that 2 CO₂ molecules were captured per polymeric anthraquinone repeating unit. With a low loading of electroactive polymer on the overall electrode, a good CO₂ uptake capacity of 0.17 mmol_CO2 g_p-1-AAQ+CP^-1 based on the whole immersed electrode mass was achieved. Electrochemical impedance spectroscopy revealed that differences in interface resistance between the polymer and the electrolyte contribute to this disparity, particularly at lower potentials where glassy carbon shows suppressed unwanted side reactions.