(a) The unit cell of side view for the bulk 2H-MoS2 crystal. (b) Top view of six different adsorption sites of monolayer and bilayer MoS2 sheets with the 4 × 4 × 1 supercell. Side view of the final relaxed adsorbed configurations: (c) for the TMo adsorption site of monolayer MoS2 sheet, (d) for the TMo adsorption site of bilayer MoS2 sheet, and (e) for the BMo adsorption site of bilayer MoS2 sheet.
(a)–(c) Top view of the difference charge densities on the plane that pass through Fe adatoms. (d)–(f) Side view of the difference charge densities on planes that pass through the Fe adatom and bonding S atoms. (a) and (d) The TMo site absoption for monolayer MoS2; (b), (e) the TMo site absoption for bilayer MoS2; and (c), (f) the BMo site absoption for bilayer MoS2.
DOS of the monolayer and bilayer MoS2: (a) Pristine monolayer MoS2, (b) Pristine bilayer MoS2, (c) monolayer MoS2 adsorbed with Fe adatom on its surface, (d) bilayer MoS2 adsorbed with Fe adatom on its surface, (e) bilayer MoS2 adsorbed with Fe atom in its interlayer. Black and red lines are for majority and minority spin states, respectively. The dashed vertical lines indicate the Fermi levels.
LDOS of the Fe adatom in the BMo site. Values of LDOS at the Fe 4s and 3d orbitals are shown in (a) and (b), respectively. The Fermi level is set to zero and denoted by the vertical dashed line (black).
Summary of results for Fe adatom adsorbed monolayer and bilayer MoS2 sheets. The adsorption energy is defined as the difference between total spin-polarized energy of Fe–molybdenum disulfide system with different adsorption configurations and the total energy of the isolated MoS2 sheet and Fe atom in its ground state. The number of nearest sulfur atoms is indicated in parentheses following the value of the Fe–S bond length (Å). The height (Å) is the perpendicular distance from the Fe adatom to the initial surface plane of MoS2 layer. The values of the magnetic moment μ(μB ) are for the local magnetic moments of the Fe adatom. The magnetic moment, bond length, and height are for the most stable configurations (TMo and BMo sites). Monolayer-Surface and Bilayer-surface indicates Fe adatoms adsorbed on the surfaces of monolayer and bilayer MoS2 sheets, respectively. Bilayer-interlayer is the bilayer MoS2 sheet adsorbed with Fe adatom in its interlayer.
Charge transfers from Fe adatoms to monolayer and bilayer MoS2 sheets (Te). 4s/3d denotes the valence electron configuration for a free standing Fe atom. 4s*/3d*/4p* is the valence electron configuration corresponding to the Bader charge analysis and LDOS of the Fe atom adsorbed on MoS2 sheet. Δs/s and Δd/d are the electron migration rates for 4s and 3d orbitals of the Fe adatom, respectively. The negative symbol refers to the electrons drawn out from s orbitals.
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