Structural characterization and thermal stability of MoS2 intercalation compounds

The intercalation of MoS2 with Co and Fe complexes has been accomplished via exfoliation of LixMoS2 by reaction with water, followed by flocculation in the presence of cationic guest species. The resulting self-assembled compounds have been characterized by X-ray absorption spectroscopy, electron diffraction, powder X-ray diffraction, and magnetic measurements. The 2H-type (undistorted) MoS2 undergoes a structural distortion to 1T-type MoS2 during the Li intercalation, which is partially maintained upon exfoliation and flocculation. A structural model of 1T-MoS2 is proposed on the basis of X-ray absorption spectroscopy and electron diffraction, in which the unit cell has P3 symmetry with lattice parameters a = 6.52(5) Angstrom, c = 6.14 Angstrom. The Mo atoms are shifted approximately 0.5 Angstrom from their positions in 2H-MoS2 to farm trigonal clusters in 1T-MoS2, with a concomitant change in coordination geometry from trigonal prismatic to distorted octahedral. Layers of Co(OH)(2) were intercalated between the distorted and/or undistorted layers of MoS2 when either Co2+ or Co3+ complexes were used as the flocculating ion. Flocculation of exfoliated MoS2 with (eta(5)-C5H5)(2)M+ (M = Fe, Co) resulted in intercalation of monolayers of the metallocenium cations between the partially negatively charged MoS2 sheets.