Mg 12 O 12 and Be 12 O 12 Nanocages as Sorbents and Sensors for H 2 S and SO 2 Gases: A Theoretical Approach.

Theoretical calculations based on the Density Functional Theory (DFT) have been performed to investigate the interaction of H 2 S as well SO 2 gaseous molecules at the surfaces of Be 12 O 12 and Mg 12 O 12 nano-cages. The results show that a Mg 12 O 12 nano-cage is a better sorbent than a Be 12 O 12 nano-cage for the considered gases. Moreover, the ability of SO 2 gas to be adsorbed is higher than that of H 2 S gas. The HOMO-LUMO gap (E g ) of Be 12 O 12 nano-cage is more sensitive to SO 2 than H 2 S adsorption, while the E g value of Mg 12 O 12 nano-cage reveals higher sensitivity to H 2 S than SO 2 adsorption. The molecular dynamic calculations show that the H 2 S molecule cannot be retained at the surface of a Be 12 O 12 nano-cage within 300-700 K and cannot be retained on a Mg 12 O 12 nano-cage at 700 K, while the SO 2 molecule can be retained at the surfaces of Be 12 O 12 and Mg 12 O 12 nano-cages up to 700 K. Moreover, the thermodynamic calculations indicate that the reactions between H 2 S as well SO 2 with Be 12 O 12 and Mg 12 O 12 nano-cages are exothermic. Our results suggest that we can use Be 12 O 12 and Mg 12 O 12 nano-cages as sorbents as well as sensors for H 2 S and SO 2 gases.