Selective gas adsorption on Pd- and Ti-decorated MoS2/silicene heterostructures: A DFT combined with machine-learning study

Using density functional theory (DFT) and machine learning, this study explores the adsorption of H 2 , NH 3 , and NO 2 on Pd- and Ti-decorated MoS 2 /silicene heterostructures. Adsorption energies reveal three stable configurations: H 2 -Pd, NH 3 -Ti, and NO 2 -Ti, with NO 2 -Ti showing the strongest interaction. DOS, PDOS, and charge density difference analyses indicate strong hybridization between Ti-decorated MoS 2 /silicene and N/O atoms, while H 2 interacts weakly with Pd sites. CGCNN predictions show that Ti decoration enhances mechanical strength, whereas gas adsorption reduces bulk and shear moduli. Optical and electronic parameters-including JDOS, dielectric function, conductivity, and Seebeck coefficient-change significantly after adsorption, especially for NO 2 . These findings highlight the potential of transition-metal-decorated MoS 2 /silicene as a promising theoretical platform for selective gas sensing based on electro-optical responses. (a) Top view of MoS 2 /silicene heterostructures, (b) side view of H 2 /NH 3 /NO 2 adsorbed on Pd/Ti-decorated MoS 2 /Silicene heterostructures. • Pd/Ti decoration creates active sites on MoS 2 /silicene for gas adsorption. • H 2 -Pd, NH 3 -Ti, and NO 2 -Ti are the most stable adsorption configurations. • NO 2 shows strong chemisorption; NH 3 exhibits moderate interaction suitable for sensing. • Gas adsorption modifies magnetic, thermoelectric, and optical properties. • The system provides insights into intrinsic gas–surface interactions in 2D materials.