Mg₁₂O₁₂ and Be₁₂O₁₂ Nanocages as Sorbents and Sensors for H₂S and SO₂ Gases: A Theoretical Approach

Theoretical calculations based on the Density Functional Theory (DFT) have been performed to investigate the interaction of H₂S as well SO₂ gaseous molecules at the surfaces of Be₁₂O₁₂ and Mg₁₂O₁₂ nano-cages. The results show that a Mg₁₂O₁₂ nano-cage is a better sorbent than a Be₁₂O₁₂ nano-cage for the considered gases. Moreover, the ability of SO₂ gas to be adsorbed is higher than that of H₂S gas. The HOMO-LUMO gap (E_g) of Be₁₂O₁₂ nano-cage is more sensitive to SO₂ than H₂S adsorption, while the E_g value of Mg₁₂O₁₂ nano-cage reveals higher sensitivity to H₂S than SO₂ adsorption. The molecular dynamic calculations show that the H₂S molecule cannot be retained at the surface of a Be₁₂O₁₂ nano-cage within 300-700 K and cannot be retained on a Mg₁₂O₁₂ nano-cage at 700 K, while the SO₂ molecule can be retained at the surfaces of Be₁₂O₁₂ and Mg₁₂O₁₂ nano-cages up to 700 K. Moreover, the thermodynamic calculations indicate that the reactions between H₂S as well SO₂ with Be₁₂O₁₂ and Mg₁₂O₁₂ nano-cages are exothermic. Our results suggest that we can use Be₁₂O₁₂ and Mg₁₂O₁₂ nano-cages as sorbents as well as sensors for H₂S and SO₂ gases.