Adsorption of gases on B12N12 and Al12N12 nanocages

Density functional theory (DFT) was used to investigate the adsorption of twenty-four gases (SiH4, H-2, Cl-2, F-2, CF4, CH4, CF2Cl2, N-2, CHF3, OCS, N2O, AsH3, CH3Cl, COCl2, C2H2, C2H4, H2Se, H2S, PH3, COF2, CH3F, HCHO, (CH3)(2)O, and CH3NH2) on B12N12 and Al12N12 nanocages. Most of the studied gases are weakly (strongly) adsorbed on the B12N12 (Al12N12) nanocage. However, AsH3, H2Se, H2S, PH3, CH3F, HCHO, (CH3)(2)O, and CH3NH2 are strongly adsorbed on the B12N12 nanocage and H-2, F-2, CF4, CH4, and CF2Cl2 are weakly adsorbed on the Al12N12 nanocage. The most negative-valued molecular electrostatic potential (MESP) minimum (V-min) corresponds to the electron-rich region (e.g., lone pair and pi-bond) in the molecule. An important observation is that the adsorption energies of the gases on the B12N12 and Al12N12 nanocages are well correlated with the MESP V-min values of the gases. Substantial changes are found in the DFT reactivity indices like chemical potential and hardness of the B12N12 and Al12N12 nanocages, mainly due to the strong gas adsorption. The quantum theory of atoms in molecules analysis suggests the covalent nature of interactions only in the AsH3/B12N12, H2Se/B12N12, H2S/B12N12, and PH3/B12N12 systems.