Investigation of carbon monoxide adsorption onto sumanene (C21H12) decorated with Li+ ions toward its elimination

One of the important techniques to attract gaseous pollutant is placement of metals or their cations on carbon-based materials. In this study, Li+ ions were applied in order to promote adsorption of CO gas on sumanene bowl-shaped nanostructure. The results of theoretical calculations at MP2/6-311+G(d,p)//B3LYP/6-31G(d) level showed that the binding energy (BE) for chemisorption of Li+ ions on sumanene in convex faces is higher than concave one and decreases with the number of Li+ from one to three. It is observed that above Li+ ions or between them in bridge form at inner surface of Li+-sumanene configurations are the most appropriate sites for CO trapping. The CO-Li+-sumanene systems possessed the higher BE than CO-sumanene systems. Natural population analysis (NPA) and natural bond orbital (NBO) analysis obviously revealed that charge distribution in sumanene is affected by lithium ions and not by CO molecules. Besides, density of state (DOS) curves specified that the energy gap in Li+-sumanene reduced considerably after CO attraction. Consequently, decorated sumanene by Li+ ions is appropriate sorbent for removal CO contaminant from environment.