凯发

We have produced a variety of 2D nanosheets by exfoliating layered transition metal oxides into colloidal single layers. [1,2] Osmotic swelling induced by reaction with aqueous amine solutions to homogeneously prop the interlayer gallery up to a hundred times is a key step for high-yield production of unilamellar nanosheets. [3,4] The resulting 2D oxide crystals have a molecularly thin morphology, which is similar to graphene. On the other hand, these nanosheets are characterized by their rich varieties in composition and structure, which leads to a range of functionalities. For example, Ti or Nb oxide nanosheets of Ti1-dO24- and Ca2Nb3O10- work as wide-gap semiconductors, showing photocatalytic property, while Mn- or W-based oxide nanosheets such as MnO20.4- and Cs2W11O362- show redox activity and chromic property. 

These nanosheets are useful as a building block to be assembled into various nanostructures such as nanocomposites, nanofilms and hydrogels.[1,2,5] Particularly, solution-based processes involving sequential adsorption and Langmuir-Blodgett deposition are powerful to tailor precisely organized nanostructured films. Versatile function design, for example, photochemical energy storage, high-k dielectrics, can be achieved by this approach.

References:

[1] R. Ma and T. Sasaki, Adv. Mater. 22, (2010) 5082. 

[2] L. Z. Wang and T. Sasaki, Chem. Rev. ASAP article (DOI: 10.1021/cr400627u).

[3] F. Geng, R. Ma, A. Nakamura, K. Akatsuka, Y. Ebina, Y. Yamauchi, N. Miyamoto, and T. Sasaki, Nat. Commun. 4 (2013) 1632.

[4] F. Geng, R. Ma, Y. Ebina, Y. Yamauchi, N. Miyamoto, and T. Sasaki, J. Am. Chem. Soc. 136 (2014) 5491.

[5] M. Osada and T. Sasaki, Adv. Mater. 24 (2012) 210.