A wide variety of cation-exchangeable layered transition metal oxides and their relatively rare counterparts, anion-exchangeable layered hydroxides, have been exfoliated into individual host layers, i.e., nanosheets. Exfoliation is generally achieved via a high degree of swelling, typically driven either by intercalation of bulky organic ions (quaternary ammonium cations, propylammonium cations, etc.) for the layered oxides or by solvation with organic solvents (formamide, butanol, etc.) for the hydroxides. Ultimate two-dimensional (2D) anisotropy for the nanosheets, with thickness of around one nanometer versus lateral size ranging from submicrometer to several tens of micrometers, allows them to serve either as an ideal quantum system for fundamental study or as a basic building block for functional assembly. The charge-bearing inorganic macromolecule-like nanosheets can be assembled or organized through various solution-based processing techniques (e.g., flocculation, electrostatic sequential deposition, or the Langmuir-Blodgett method) to produce a range of nanocomposites, multilayer nanofilms, and core-shell nanoarchitectures, which have great potential for electronic, magnetic, optical, photochemical, and catalytic applications.

Nanosheets of oxides and hydroxides: Ultimate 2D charge-bearing functional crystallites.

Titanium Oxide Nanosheets: Graphene Analogues with Versatile Functionalities

3D Hierarchical orientation in polymer -clay nanocomposite films

Densely packed exfoliated nanosheet films such as Ti0.91O2, Ti0.8M0.2O2 (M = Co, Ni), Ti0.6Fe0.4O2, and Ca2Nb3O10 on solid substrates were prepared by the LB transfer method without any amphiphilic additives at the air−water interface. Nanosheet crystallites covered nearly 95% on the solid surface with minimum overlapping of nanosheets. The LB transfer method of the Ti0.91O2 nanosheet monolayer film is applicable for not only hydrophilic substrates such as quartz, silicon, indium−tin oxide (ITO), and glass but also the hydrophobic Au surface. On the basis of these points, the LB transfer method has advantages compared to the alternating layer-by-layer method, which makes use of oppositely charged polyelectrolytes such as poly(ethylenimine) (PEI). Adsorption of hydrophobic Ti0.91O2 nanosheets at the air−water interface is responsible for this LB transfer deposition method. The addition of tetrabutylammonium bromide into the subphase assisted the adsorption, causing an increase in the adsorbed amount of Ti0...

Fabrication of Densely Packed Titania Nanosheet Films on Solid Surface by Use of Langmuir−Blodgett Deposition Method without Amphiphilic Additives

https://dr.ntu.edu.sg/bitstream/10356/101598/1/Roles%20of%20Graphite%20Oxide%2c%20Clay%20and%20POSS%20during%20the%20Combustion%20of%20Polyamide%206.pdf

Roles of graphite oxide, clay and POSS during the combustion of polyamide 6

First observation of in-plane X-ray diffraction arising from a single layered inorganic compound film by a grazing incidence X-ray diffraction system with a conventional laboratory X-ray source

We have developed a novel method of modifying a solid surface with a single-layered film of anionic phyllosilicate as an anchor of cationic functional molecules. According to the method, a hybrid film of octadecylammonium and montmorillonite layer was deposited onto a Si substrate by the Langmuir−Blodgett method. Thereafter the Si substrate was immersed in methanol to remove an organic layer, leaving a single-layered montmorillonite film. As a final step, a cationic chiral molecule, Δ-[Ru(phen)3]2+ (phen = 1,10-phenanthroline), was self-assembled from its aqueous solution onto the single-layered montmorillonite film. The thickness of a single-layered montmorillonite film was estimated to be ca. 1.5−1.6 nm by atomic force microscopy observation. The thickness of the film increased to ca. 2.6−2.7 nm after the self-assembly treatment. The results were consistent with the analyses of interference oscillation patterns of specular X-ray reflectivity (SXR) curves. From the analyses of SXR curves, the thickness o...

Noboru Wakabayashi

Papers

First observation of in-plane X-ray diffraction arising from a single layered inorganic compound film by a grazing incidence X-ray diffraction system with a conventional laboratory X-ray source

Design of a Chiral Surface by Modifying an Anionically Charged Single-layered Inorganic Compound with Metal Complexes

The effect of ΔΛ chirality on molecular organization in two-dimensional films of a Ru(II) complex with a mesogenic ligand

Racemic adsorption of tris(1,10-phenanthroline)ruthenium(ii) onto a mica surface

Nanometer-scale ordering in cast films of columnar metallomesogen as revealed by STM observations