Electronic, magnetic, optical, and edge-reactivity properties of semiconducting and metallic WS₂ nanoribbons

First-principles density functional theory calculations are performed in one-dimensional single-layer WS2 nanoribbons with zigzag- and armchair-edges. Magnetic ordering, optical response, and chemical reactivity are investigated. Our results demonstrated thatWS2 zigzag nanoribbons exhibit a ferromagnetic- metallic behavior that is attributed to the edges; the resulting magnetic moments are mainly localized in S andWedge atoms. Furthermore, the magnetic ordering along the edges depends on the zigzag nanoribbon's width. Armchair nanoribbons exhibit semiconducting behavior. Optical response results demonstrated that there exists a strong optical polarization anisotropy enhancing a well defined absorption intensity peak, with polarization along the nanoribbons axis. Regarding chemical reactivity, ribbons are exposed to water (H₂O), thiophene (C₄H₄S), and carbon monoxide (CO) molecules. Results reveal thatH₂Ocan be covalently joined to the edges via the W-Atoms in the ribbons with zigzag-edges, whereas in ribbons with armchair edges,H₂Ois dissociated inOHand H, and these species are joined toWand S atoms respectively. Results for thiophene on zigzag nanoribbons demonstrated thatC₄H₄S molecules are absorbed by W-terminated edges, whereas in armchair ribbons, theC₄H₄S is linked to the edges by binding to the sulfur. Interestingly,COmolecules give rise to half-metallicity and surprising ferromagnetism in zigzag and armchair nanoribbons, respectively. The results discussed here could help to understand the physical and chemical properties of edges in transition metal dichalcogenides materials.