First-Principles Investigation of H₂S Adsorption on (ZnO)14 Nanoclusters: Electronic, Vibrational, and Topological Insights
نویسندگان
1 Department of Chemistry, College of Sciences for Women, University of Babylon, Iraq
2 Department of Medical Laboratories Technology, AL-Nisour University College, Baghdad, Iraq
3 Department of Chemistry, College of Sciences for Women, University of Babylon, Iraq
4 Department of Pharmaceutics, College of Pharmacy, University of Al-Ameed, Iraq
5 College of Pharmacy, Ahl Al Bayt University, Kerbala, Iraq
6 Department of Medial Laborites, Al-Manara College For Medical Sciences, Maysan, Iraq
7 Department of Chemistry, College of Sciences for Women, University of Babylon, Iraq
doi
10.22052/JNS.2025.04.015چکیده
The efficient detection and capture of hazardous gases like hydrogen sulfide (H₂S) are vital for environmental monitoring and industrial safety. In this study, we perform a comprehensive theoretical analysis of H₂S adsorption on a (ZnO)14 nanocluster using density functional theory (DFT) and time-dependent DFT (TD-DFT). Structural optimizations, frontier molecular orbital (FMO) analysis, Mulliken charge distribution, vibrational frequency calculations (FT-IR), adsorption energy, and Atoms in Molecules (AIM) topological analysis were conducted to investigate the electronic and physicochemical properties before and after gas adsorption. The adsorption energy calculations confirmed that H₂S undergoes chemisorption on the ZnO surface, with an energy of interaction indicating favorable thermodynamics. FMO analysis showed a significant reduction in the HOMO–LUMO gap from 7.94 eV (H₂S) and 0.16 eV (ZnO) to 0.43 eV for the H₂S/ZnO complex, suggesting enhanced electronic conductivity and potential sensor activity. AIM analysis revealed weak to moderate interactions between the adsorbate and the surface, with positive Laplacians (∇²ρ) and low-to-moderate electron density (ρ) at the bond critical points, indicating partially covalent character. Importantly, the IR spectral analysis demonstrated a marked shift and broadening of characteristic H₂S vibrational modes upon adsorption. Notably, the S–H stretching modes at ~2600 cm⁻¹ were either red-shifted or disappeared entirely in the H₂S/ZnO complex, while new modes corresponding to Zn–S and O–H stretching appeared in the fingerprint region, confirming strong interaction and structural reorganization. These vibrational changes validate the adsorption mechanism predicted by energy and charge analyses.
