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Titanate (IV) nanosheets (TiNSs) have a 2D structure where TiO6 octahedra are edge-linked in a lepidocrocite-type 2D lattice〔Osada, Minoru, and Takayoshi Sasaki. "ChemInform Abstract: Two-Dimensional Dielectric Nanosheets: Novel Nanoelectronics from Nanocrystal Building Blocks." ChemInform 24 (2012): 210-28. Print.〕 with chemical formula HxTi2—x/4☐x/4O4 ⦁ H2O (x~0.7; ☐, vacancy).〔Sasaki, Takayoshi, Mamoru Watanabe, Hideo Hashizume, Hirohisa Yamada, and Hiromoto Nakazawa. "Macromolecule-like Aspects for a Colloidal Suspension of an Exfoliated Titanate. Pairwise Association of Nanosheets and Dynamic Reassembling Process Initiated from It." Journal of the American Chemical Society (1996): 8329-335. Print.〕 Titanate nanosheets may be regarded as sheets with molecular thickness and infinite planar dimensions. TiNSs are typically formed via liquid-phase exfoliation of protonic titanate. In inorganic layered materials, individual layers are bound to each other by van der Waals interactions if they are neutral, and additional Coulomb interactions if they are composed of oppositely charged layers. Through liquid-phase exfoliation, these individual sheets of layered materials can be efficiently separated using an appropriate solvent, creating single-layer colloidal suspensions.〔M. Brown. Exfoliating layered materials. Feb. 2011. http://www.rsc.org/chemistryworld/News/2011/February/03021103.asp〕 Solvents must have an interaction energy with the layers that is greater than the interaction energy between two layers.〔 ''In situ'' X-Ray diffraction data indicates that TiNSs can be treated as macromolecules with a sufficient amount of solvent in between layers so that they behave as individual sheets.〔 == Properties== Unilamellar TiNSs have a number of unique properties, and are said to combine those of conventional titanate and titania. Structurally, they are infinite ultrathin (~0.75 nm) 2D sheets with a high density of negative surface charges originating from the oxygen atoms at the corners of the adjoint octahedrons〔Liu, M., Y. Ishida, Y. Ebina, T. Sasaki, T. Hikima, M. Takata, and T. Aida. "An Anisotropic Hydrogel with Electrostatic Repulsion between Cofacially Aligned Nanosheets." Nature 517.7532 (2014): 68. Print.〕 . TiNSs may balance this anionic charge by inserting a counterionic layer between the two sheets either via layering or in aqueous solution. This electric double layer gives the material flexible interlayer distances,〔Huang, Jiquan, Yongge Cao, Zhonghua Deng, and Hao Tong. "Formation of Titanate Nanostructures under Different NaOH Concentration and Their Application in Wastewater Treatment." Journal of Solid State Chemistry (2011): 712-19. Print.〕 high cation exchange capacity,〔 and excellent dielectric capabilities.〔 Typically, titanium oxide suffers from oxygen vacancies, which diminish its potential as capacitors due to vacancies acting as high-leakage paths and charge carrier traps,〔 however, TiNSs possess Ti vacancies, which promote channels for electron transfer.〔 When Ti vacancies are present, the effective charge felt by electrons on oxygen atoms reduces and allows less hindered electron motion.〔Ohwada, Megumi, Koji Kimoto, Teruyasu Mizoguchi, Yasuo Ebina, and Takayoshi Sasaki. "Atomic Structure of Titania Nanosheet with Vacancies." Scientific Reports (2013). Web. 1 Mar. 2015.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Titanate nanosheet」の詳細全文を読む スポンサード リンク
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