Trimetallic Defects on MoS₂ Monolayers toward the Adsorption of Diatomic Pollutants

An investigation, within dispersion-corrected density functional theory, of the electronic and magnetic behavior of diatomic molecules adsorbed on modified MoS₂ monolayers containing coinage metals embedded in sulfur trivacancies is reported. The selective electronic responses induced by gas adsorption highlight the strong potential of these systems for gas-sensing applications. Attention is given to small diatomic molecules of environmental relevance, such as NO, CO, and O₂, whose mitigation and/or detection remain critical challenges. Results demonstrate that incorporation of group 11 metals into sulfur vacancies significantly enhances the adsorption capability of MoS₂ monolayers. Strong adsorption energies, reaching up to -46.157 kcal·mol^-1 (-2.001 eV), are observed, especially in Cu-doped systems, indicating their suitability for gas capture and sensing. Density of states and projected density of states analyses reveal notable changes in the electronic structure upon adsorption. In particular, a copper trimer embedded into a trivacancy of sulfur exhibits state splitting upon CO adsorption on it, identifying it as a promising chemiresistive sensor candidate. The Ag- and Au-doped systems interacting with NO display pronounced modifications in their PDOS profiles and magnetic moments, with total magnetic moments exceeding 1 μ_B and half-metallic behavior that favors spin-up electron conduction. These charge-transfer and magnetic responses enable tunable electronic and magnetic properties. This work provides valuable insight into defect-engineered MoS₂ monolayers and establishes embedded coinage metals as effective design elements for advanced environmental monitoring and pollutant detection sensors but limited by the continuous introduction of defect states in the bandgap.