Thermodynamic and Spectroscopic Characterization of Ch₄, Co₂, and Nh₃ Adsorption on Silver Nanoclusters via Dft Methods

Abstract In this study Density Functional Theory (DFT) calculations, carried out using Gaussian 16 are employed to explore the interactions between environmentally significant toxic gas molecules methane (CH₄), carbon dioxide (CO₂) and ammonia (NH₃) and its adsorption on silver nanoclusters (Ag₃). These interactions are investigated to understand their potential applications in pollutant detection and environmental monitoring. The structural and electronic properties Ag₃-X (X = CH₄, CO₂, NH₃) complexes are optimized and analysed through molecular orbital calculations, including HOMO-LUMO gaps, Band gaps and Molecular Electrostatic Potential (MEP) maps. Key thermodynamics parameters such as binding energy, free energy and adsorption energies are calculated to evaluate adsorption efficiency. The study also examines vibrational properties via Surface Enhanced Raman Scattering (SERS), providing detailed Raman spectra that highlight shifts in frequency and intensity upon gas adsorption which helps in predicting the stability of the analyte-Ag cluster composite. The results demonstrate the utility of silver nanoclusters as sensitive, selective platforms for detecting trace levels of atmospheric pollutants. This computational approach underscores the value of hybrid DFT methods in designing sustainable nano materials for real-time environmental sensing applications