Electrophoretic deposition of negatively charged tetratitanate nanosheets and transformation into preferentially oriented TiO2(B) film

A tetrabutylammonium-H2Ti4O9.xH(2)O intercalation compound was obtained by a guest exchange reaction between tetrabutylammonium hydroxide and an ethylammonium-H2Ti4O9.xH(2)O intercalation compound, and its dispersion state in aqueous and non-aqueous solutions were studied. Spontaneous exfoliation of H2Ti4O9.xH(2)O into colloidal nanosheets occurred when the tetrabutylammonium-H2Ti4O9.xH(2)O intercalation compound was dispersed in water, methyl alcohol, isopropyl alcohol, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, and propylene carbonate, while exfoliation did not occur in tetrahydrofuran. A tetrabutylammonium-H2Ti4O9.xH(2)O film was obtained by a reassembly process by casting the colloidal suspension containing exfoliated nanosheets, while a H2Ti4O9.xH(2)O film was directly obtained by electrophoretic deposition. Thermal treatment of the electrophoretically deposited film led to an oriented TiO2 (B) film with the (0k0) planes lying perpendicular to the substrate.