Adsorption of Gases on Fullerene-like X12Y12 (X = Be, Mg, Ca, B, Al, Ga, C; Y = C, Si, N, P, O) Nanocages

Density functional theory calculations are carried out to investigate the adsorption behaviors of CO2, NO, CO, and NH3 on 12 fullerene-like X12Y12 (B12N12, Al12N12, Ga12N12, B12P12, Al12P12, Ga12P12, Be12O12, Mg12O12, Ca12O12, C12Si12, C12N12, and C24) nanocages. The molecular electrostatic potential (MESP) analysis suggests that, for example, for the B12N12, Al12N12, and Ga12N12 nanocages, the electron-rich regions are centered on the N atoms. The deepest MESP minimum (Vmin) values suggest that replacement of C atoms in C24 by XY units increases the electron-rich nature of the nanocage. Generally, CO2 is found to be physisorbed, while NH3 is chemisorbed on the X12Y12 nanocages. NO is found to be strongly adsorbed on the B12P12, Be12O12, Ca12O12, and C24 nanocages, and CO is strongly adsorbed on the B12N12, B12P12, Be12O12, and C24 nanocages. An important result is that the Vmin values of the X12Y12 nanocages are linearly proportional to their CO2 or NO adsorption energies. The quantum theory of atoms in molecules analysis suggests strong covalent interactions in the CO2/Ca12O12, NO/Ca12O12, NO/C24, CO/C24, and NH3/C24 systems.