X-ray absorption fine structure study of the atomic and electronic structure of molybdenum disulfide intercalation compounds with transition metals

The local structures of 'host' and 'guest' layers of MoS2 intercalated with M(OH)(2) (M = Mn, Co, and Ni) prepared via interaction of single-layer MoS2 dispersions and solutions of M2+ salts were studied by X-ray absorption spectroscopy. According to M K-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) results, the electronic structure and atomic environment of the M atoms in the intercalates are similar to that of the crystalline hydroxides M(OH)(2). In the Ni intercalate, Mo K-edge EXAFS revealed a structural change of the 'host' MoS2 layers similar to that reported for water dispersions of MoS2 single layers. S K-edge XANES data indicate that the change is associated with increased electron density on the S atoms in the matrix. SO42- and Mon+ (4 < n < 6) were detected in the intercalated materials exposed to air, suggesting that transition metal intercalation may increase the susceptibility of the MoS2 layers to oxidation. (C) 1998 Elsevier Science S.A. All rights reserved.