). This can be explained by greater porosity of GR-AC, which allows faster mass transfer, and improved kinetics. The productivity of the electrodes followed the same trend as the volumetric adsorption capacity, with GP-AC and GS-AC showing the highest productivities of 46.1 mmol.h -1 .m -2 and 39.9 mmol.h -1 .m -2 , respectively. Since fast sorption kinetics and high productivity are directly related to the cost of CO2 capture, a further increase in CO2 adsorption rate and productivity would be highly desirable for SSA. Studies that quantitatively determine the factors that limit kinetics should be performed. One possibility is that slow CO2 hydrolysis in the neutral electrolyte limits the kinetics. This could be addressed by the addition of CO2 hydrolysis catalysts to the electrolyte. Possibly, also the pore surfaces of the activated carbon could be modified so that the carbon acts as a heterogeneous catalyst. In our XPS studies, GR-AC and GP-AC showed a higher degree of -OH functionality while GS showed both -OH and C-N functionality, and these three biomass-derived carbons exhibit the highest adsorption rates. These results argue that pore surfaces with nucleophilic, chemical functionalities may enhance the CO2 sorption rates during capacitive charging/discharging of the electrodes.