M-Encapsulated BeO Nano-Cage (M = K, Mn, or Cu) for CHO 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 CHO molecule on BeO and MBeO nano-cages (M = K, Mn, or Cu atom). The energy gap for BeO was 8.210 eV, while the M encapsulation decreased its value to 0.685-1.568 eV, whereas the adsorption of the CHO gas decreased the E values for BeO and CuBeO to 4.983 and 0.876 eV and increased its values for KBeO and MnBeO to 1.286 and 1.516 eV, respectively. The M encapsulation enhanced the chemical adsorption of CHO gas with the surface of BeO. The UV-vis spectrum of the BeO nano-cage was dramatically affected by the M encapsulation as well as the adsorption of the CHO gas. In addition, the adsorption energies and the electrical sensitivity of the BeO as well as the MBeO nano-cages to CHO gas could be manipulated with an external electric field. Our results may be fruitful for utilizing BeO as well as MBeO nano-cages as candidate materials for removing and sensing formaldehyde gas.