M-Encapsulated Be₁₂O₁₂ Nano-Cage (M = K, Mn, or Cu) for CH₂O Sensing Applications: A Theoretical Study

DFT and TD-DFT studies of B3LYP/6-31 g(d,p) with the D2 version of Grimme's dispersion are used to examine the adsorption of a CH₂O molecule on Be₁₂O₁₂ and MBe₁₂O₁₂ nano-cages (M = K, Mn, or Cu atom). The energy gap for Be₁₂O₁₂ was 8.210 eV, while the M encapsulation decreased its value to 0.685-1.568 eV, whereas the adsorption of the CH₂O gas decreased the E_g values for Be₁₂O₁₂ and CuBe₁₂O₁₂ to 4.983 and 0.876 eV and increased its values for KBe₁₂O₁₂ and MnBe₁₂O₁₂ to 1.286 and 1.516 eV, respectively. The M encapsulation enhanced the chemical adsorption of CH₂O gas with the surface of Be₁₂O₁₂. The UV-vis spectrum of the Be₁₂O₁₂ nano-cage was dramatically affected by the M encapsulation as well as the adsorption of the CH₂O gas. In addition, the adsorption energies and the electrical sensitivity of the Be₁₂O₁₂ as well as the MBe₁₂O₁₂ nano-cages to CH₂O gas could be manipulated with an external electric field. Our results may be fruitful for utilizing Be₁₂O₁₂ as well as MBe₁₂O₁₂ nano-cages as candidate materials for removing and sensing formaldehyde gas.