First principles investigation of NO2 and NH3 adsorption on a two-dimensional CrTe monolayer with environmental interference from H2O, CO2 and N2

Abstract The adsorption behaviour of NO 2 , NH 3 , H 2 O, CO 2 , and N 2 molecules on a two-dimensional CrTe monolayer was systematically investigated using spin-polarized density functional theory (DFT) calculations to elucidate the adsorption mechanism and adsorption induced modifications in its electronic and magnetic properties. Dispersion interactions were explicitly considered using the PBE-D3(BJ) approach. The structural stability, adsorption characteristics, charge transfer, electronic structure, magnetic response, and thermal stability were analysed through optimized adsorption geometries, adsorption energy calculations, charge density difference (CDD) analysis, Mulliken population analysis, density of states (DOS), projected density of states (PDOS), spin-polarized band structures, phonon calculations, and ab initio molecular dynamics (AIMD) simulations. The calculated adsorption energies reveal that all investigated gas molecules interact favourably with the CrTe surface. NO 2 exhibits the strongest adsorption at the hollow (4-fold) site with an adsorption energy of -2.91 eV, followed by H₂O with -2.08 eV, NH₃ with -1.92 eV, CO₂ with -1.27 eV, and N₂ with -1.23 eV. Charge density difference and Mulliken population analyses demonstrate pronounced interfacial charge redistribution for NO₂ adsorption, resulting in significant modifications of the electronic and magnetic properties, whereas the other gas molecules induce comparatively weaker perturbations. DOS, PDOS, and spin-polarized band structure analyses further confirm stronger electronic coupling and adsorption induced electronic perturbations for NO 2 . Phonon and AIMD simulations confirm the dynamical and thermal stability of the CrTe monolayer. These findings provide comprehensive insight into molecule surface interactions and indicate that the CrTe monolayer is a promising platform for selective NO 2 adsorption, providing a theoretical basis for future gas-sensing studies.