Sensing of H2S, NO2, SO2, and O3 through pristine and Ni-doped Zn12O12 nanocage

Abstract

Harmful gases pose a serious threat to life on Earth therefore, their detection is quite vital for sustainable life. For this purpose the adsorption properties of harmful gases (H2S, NO2, SO2, and O3) were investigated to gain insights into the influence of adsorbed gas molecules on the electronic properties of pristine and Ni-doped Zn12O12 nanocages, and how these effects could be applied to design more sensitive gas sensing materials. Adsorption energies for these gases on pristine Zn12O12 nanocages ranged from −9.89 to −43.23 kcal/mol. The adsorption energies were further enhanced in Ni-doped Zn12O12 nanocages. The highest interaction energy was observed for the NO2@Ni-Zn12O12 complex (−85.23 kcal/mol), followed by O3@Ni-Zn12O12 (−57.42 kcal/mol). Non-covalent interaction (NCI), quantum theory of atoms in molecules (QTAIM), and electron density difference (EDD) analyses were performed for both pristine and doped complexes. The electronic properties of the complexes were studied using natural bond orbital (NBO), frontier molecular orbital (FMO), and density of states (DOS) analyses. When H2S adsorbed on pristine and doped nanocages, charge transfer occurred towards the nanocages. On the other hand, NO2, SO2, and O3 extracted charges from both types of nanocages. The highest charge transfer was observed in O3@Ni-Zn12O12 (−0.699 e−) and the lowest in H2S@Ni-Zn12O12 (0.045 e−). The largest decrease in the EH-L gap was observed for O3@Zn12O12 (2.06 eV) compared to pristine Zn12O12 nanocages (4.13 eV). In Ni-doped Zn12O12, the HOMO-LUMO gap decreased to 2.49 eV (O3@Ni-Zn12O12) and 2.32 eV (H2S@Ni-Zn12O12) from 2.79 eV (Ni-Zn12O12), indicating the sensitivity of Ni-doped Zn12O12 nanocages to O3 and H2S. Therefore, Ni-doped Zn12O12 nanocages exhibit high sensitivity to harmful gases and can be employed as highly sensitive electrochemical sensors. This study may provide valuable guidance for the design and development of new sensors for the detection of harmful gases.