Oxygen-assisted supercapacitive swing adsorption of carbon dioxide

Abstract

We report enhanced supercapacitive swing adsorption (SSA) of carbon dioxide in the presence of oxygen using activated carbon electrodes, and deliquescent, aqueous electrolytes. The presence of O2 in the gas mixture results in up to 11 times increased CO2 adsorption capacity with 3M MgBr2 and up to 4-5 times increased adsorption capacity with 3M MgCl2. Varying the oxygen concentration (5-20% O2) does not affect the energetics and adsorptive performance. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) of the electrodes demonstrate that the specific capacitance increases while the diffusion resistance decreases in the presence of oxygen, indicating enhanced pore wettability, and the reversible formation of oxygen functionalities on the pore surfaces, which enhance the adsorption. The electrodes show good performance for more than 100 hours of operation.