Nanoengineering Route to Two-Dimensional Hybrid Materials

Abstract

We have successfully synthesized inorganic-inorganic, organic-inorganic and bio-inorganic nanohybrids by applying an intercalation technique systematically to layered titanate, molybdenum disulfide (MoS₂), Bi-based cuprate superconductors (Bi₂Sr₂Ca_{m- 1}Cu_mO_y (m = 1, 2, and 3; BSCCO)), layered double hydroxides (LDHs), and clay minerals, which is of high importance in terms of basic understanding of intercalation reactions and of their practical applications. The inorganic-inorganic systems such as anatase-pillared titanate and CdS-MoS₂ hybrids were synthesized by bio-inorganic method. A novel pillaring process using an osmotic swelling was developed to prepare anatase-pillared layered titanate with large surface area, high thermal stability, and enhanced photocatalytic activity. And the intercalation of CdS nanocluster into the two dimensional MoS₂ lattice could be also realized by exfoliating and reassembling the lithiated molybdenum disulfide (LiMoS₂) in the presence of cationic CdS nanocluster in heptane solution to obtain the semiconductor-semiconductor hybrid. Metal halide-superconducting oxide hybrids such as Agl-BSCCO and HgX₂-BSCCO (X = Br, I) hybrids were also achieved via intercalation route, which can be considered as the excellent examples of inorganic/inorganic hybrid sysyem. On the other hands, the organic-inorganic hybrids were also demonstrated via intercalative complexation of iodine intercalated BSCCO with an organic salt of Py-C_nH_2n+1I (Py = pyridine). This superconducting hybrid has an unique structural feature with a sequential array of superconducting-insulating-superconducting-....layers along the c-axis, which can be regarded as a multilayered Josephson junctions, since each superdonducting block is completely isolated by insulating organic guest layer.