Molten salt assisted self assembly (MASA) : synthesis of mesoporous metal titanate (CoTiO3, MnTiO3, and Li4Ti5O12) thin films and monoliths
Chemistry of Materials
American Chemical Society
6050 - 6057
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Please cite this item using this persistent URLhttp://hdl.handle.net/11693/25159
Mesoporous metal titanates are very important class of materials for clean energy applications, specifically transition metal titanates and lithium titanates. The molten salt assisted self-assembly (MASA) process offers a new synthetic route to produce mesoporous metal titanate thin films. The process is conducted as follows: first a clear solution that contains two solvents (namely the hydrated salt (Co(NO3)2· 6H2O or Mn(NO3)2·6H2O, or LiNO3·xH2O, and ethanol), two surfactants (cethyltrimethylammonium bromide, CTAB, and 10-lauryl ether, C12EO10), an acid and titanium source (titanium tetrabutoxide, TTB) is prepared and then spin or spray coated over a substrate to form a thin or thick lyotropic liquid crystalline (LLC) film, respectively. Finally, the films are converted into transparent spongy mesoporous metal titanates by a fast calcination step. Three mesoporous metal titanates (namely, CoTiO3, MnTiO3, and Li4Ti5O12) have been successfully synthesized and structurally/thermally characterized using microscopy, spectroscopy, diffraction, and thermal techniques. The mesoporous cobalt and manganese titanates are stable up to 500 °C and collapse at around 550 °C into nanocrystalline Co3O4− TiO2 and Mn2O3−TiO2; however, lithium titanate is stable up to 550 °C and crystalline even at 350 °C. The crystallinity and pore size of these titanates can be adjusted by simply controlling the annealing and/or calcination temperatures.