<p>The present work demonstrates a comprehensive experimental and molecular modeling study of fixed bed adsorption of CO₂ over commercial activated carbon (AC-RBAA-3). The AC-RBAA-3 was characterized using Brunauer-Emmett-Teller (BET) surface area analyzer, Scanning Electron Microscope (SEM), and Raman analyses. The lower temperature (or 298&#xa0;K) remained best for CO₂ capture over AC-RBAA-3 and allowed robust adsorption up to 1140&#xa0;s compared to the higher temperatures (328&#xa0;K; 878&#xa0;s). The breakthrough profile of CO₂ decreased with increasing feed gas flow rate because of lower residence time, especially at higher flow rates. Interestingly, the lower initial CO₂ concentration showed a better breakthrough profile compared to the higher one. The maximum CO₂ uptake of 1.18 mmol/g was accomplished at 298&#xa0;K with a flow feed rate of 5&#xa0;L/min and C_in=5%. The minimal length of mass transfer zone (L_MTZ) nearly equal to 1.77&#xa0;cm was determined with an improved capacity utilization factor (i.e., 0.965 at 298&#xa0;K). The maximum usable bed height was 23.39&#xa0;cm, with an improved efficiency of 93.57%. Additionally, the experimental results were verified by Density Functional Theory (DFT) calculations, describing that CO₂ adsorbed weakly on perfect graphite surfaces, CO₂ adsorbed weakly mainly via van der Waals interaction, with the binding energy of -21.5&#xa0;kJ/mol, while the adsorption energy of CO₂ in the pores of graphite is exothermic. However, at the amorphous site of the activated carbon, CO₂ adsorbed more strongly with the energy of -41.5&#xa0;kJ/mol, suggesting that this should be considered for further enhancement in the CO₂ adsorption efficiency of activated carbon. Charge density plots revealed that the charge transfer between CO₂ and the amorphous carbon sites was the factor contributing to the enhanced affinity of CO₂ on activated carbon, justifying its effectiveness in capturing CO₂ obtained in our experiments.</p> Graphical Abstract <p></p>