Abstract: An anatase-type titania crystal having a one-dimensional structure; a process for producing the crystal; and a dye-sensitized solar cell employing the titania crystal. The titania crystal is excellent in photocatalytic characteristics and photoelectric conversion characteristics. The process for titania crystal production is characterized by comprising: a mixing step in which an aqueous solution containing a block copolymer (A) having a hydrophobic block and a hydrophilic block is mixed with an organic solvent (C) containing a titanium alkoxide (B) dissolved therein to thereby give a liquid mixture; a reaction step in which the temperature of the liquid mixture is set at a value in the range of from 120° C. to 180° C. and the pressure of the atmosphere is set so as to result in the saturated vapor pressure at that set temperature to thereby react the liquid mixture and form a titania sol; and a baking step in which the titania sol is heated to produce baked titania particles having a wire shape.

Abstract: Various metal oxide nanosheets with uniform thickness under mild conditions and in a short time are provided. A mixed solution containing a surfactant such as laurylamine and a metal alkoxide are allowed to flow over water surface to obtain a composite nanosheet. The composite nanosheet comprises a lamella molecular film consisting of a surfactant, and a metal oxide nanosheet formed along the surface of the molecular film. If necessary, the composite nanosheet was separated and then immersed in a solvent in which the surfactant can be dissolved, to separate the metal oxide nanosheet from the molecular film.